I have been aware of the Longmoor Military Railway for some time now. I knew nothing of the Bicester Military Railway until my wife and I had part of a weekend in the area. We were travelling along the M40 and using Satnav and we noticed and interesting area off to the East of the motorway which was just visible on the Satnav. Our initial thought was that there might have been some opencast workings in the area.
From looking at maps, we must have seen the area around Upper Arncott on the Satnav. It stood out far more clearly on the Satnav than it seems to do on the adjacent map. We thought that it would be good to investigate what we had seen. All we could manage was to drive through the area on the way to a wedding that we were attending.
Although some of the original railway appears to have been removed, much is still in place.
Further investigation seemed in order!
I have discovered that the Bicester Military Railway (BMR) is now a scheduled monument. It was the primary mode of transport at the Central Ordnance Depot Bicester.  It was opened in 1942 as part of the war effort. It belongs to the Ministry of Defence and links the military depots at Piddington, Arncott and Graven Hill with the Oxford to Bicester Line. The BMR has no road bridges. All of its crossings of public roads at Ambrosden, Arncott and between Arncott and Piddington are level crossings. 
Historic England provides the following information: 
Work on surveying the land for the rail system commenced in April 1941 and the 2.6 miles of railway that circled Graven Hill was pegged out ready for construction by August 1942. Track laying was well underway by the following month. Initially the entire track was to be laid using ‘philplug’ concrete sleepers and the rails were held in place by simple bearing plates and ‘dog’ spikes. These sleepers were found to be unsatisfactory and were replaced by different types of concrete sleeper; including those manufactured by Stent that can still be found at a number of points on the railway, especially within the spurs leading into the storage hangars.
Elsewhere on the system, once it was realised that the concrete sleepers were highly visible at night, it was intended to replace them with conventional timber sleepers; however, limitations on the supply of timber dictated that some of the concrete sleepers were retained and these were painted with a thin coat of black bituminous paint to tone them down.
The concrete sleepers that were gathered up after replacement were not wasted and they were put to a number of alternative uses, including the building of passenger platforms. Six passenger platforms were built around the Graven Hill depot – Langford Farm Halt (demolished), E2 Platform (demolished), Westacott Platform (partially demolished), D6 Platform (demolished), Queens Platform (demolished), and Graven Hill Platform. Fragmentary remains of the Westacott Platform can still be found to the west of the level-crossing gates on Westacott Road, and Graven Hill platform adjacent to the running line within the Sorting Sidings complex is the only fully extant example left. In addition to these improvised passenger platforms, a purpose-built ramped two-road loading / unloading bay was built in the gun park for the handling of artillery pieces.
The scale of the operations during the Second World War can be appreciated when it is realised that up to seventeen steam locomotives were working virtually around the clock to receive, sort, deliver, recover, and despatch wagons to the various storage hangars and sidings. During 1944 with the build up to D-Day and the supply of the invasion forces in Europe, 78,623 wagons were received and 77,896 were despatched through the exchange sidings; together with135,034 internal movements, this gives a grand total of 291,554 wagons being handled during one year.
Initially all train movements were controlled by a manual ‘Regulator’ system, using a block system whereby the drivers of any train had to stop at a phone cabin and ring for permission to advance into the next section, all controlled from the railway control office at Graven Hill and the regulator building at Arncott.
Eventually in 1947, two redundant locking lever frames, rodding, and semaphore signals were obtained from the defunct Cairnryan Military Railway and installed at Bicester to control major rail movements on the running lines at Graven Hill and the 2-mile section to Arncott depot that ran through Ambrosden. The lever frames were installed in two new two-storey structures that resembled a civilian signal box called ‘Blockposts’; the example at Graven Hill was called ‘A’ Blockpost and it housed a 16-lever interlocking frame (SP 58417 19846).
In 1960 a two-road locomotive shed with inspection and ash pits was built together with associated locomotive yard sidings at the north western end of the Sorting Sidings. The locomotive shed was designed to hold up to six locomotives and originally this structure had a flat central roof flanked by a row of smoke ventilators over each road, with a single pitch roof dropping to the side walls. This arrangement was to allow the smoke and steam to escape up through the roof. With the withdrawal of steam locomotives and introduction of diesel locomotives in 1965, these vents were removed and replaced by simple electrically driven extraction fans, and the roof was altered to a gabled design.
During the 1980s, the old Romney hut C1 (Carriage and Wagon Shop) at C Site, Arncott was closed and the work was transferred to a new purpose-built two-road Carriage and Wagon Department workshop at Graven Hill. The workshop was constructed against the north eastern corner of the Graven Hill locomotive shed. The shed is a simple rectangular-plan steel framed structure clad with corrugated steel sheeting.
The original railway administrative centre was located at Arncott depot, but it was moved in 1978 to a new two-storey Railway Headquarters (Building D99) over-looking the southern end of the Sorting Sidings (SP 58361 19972).
The map above is clearer than the one near the top of this post. The section of the railway which feeds Piddington Depot is now abandonned. The Military railway links into the Oxford to Cambridge line close to Bicester Outlet Village. A sketch plan of the site is included below. 
As an aside, RAF Bicester was also rail served and connected to the Oxford to Cambridge line as well. The old line cannot be seen on the adjacent map, but it is clearly visible on the satellite image below. The thin black line shows the route of the branch/siding. For much of its length the line of trees betrays its path. In 2008 the route was walked and pictures were taken for the website ‘Dereliction in the Shires’.  At the time, there was little hope for the rejuvenation of the Oxford to Cambridge line.
The Bicester Military Railway (BMR) had no connection to the RAF branch/siding and was a much more significant endeavour. It served what is now the Defence, Storage and Distribution Centre (DSDC), the construction of which began in 1941. By September 1942 the Headquarters and first storehouse had opened and in 1943 the Depot assumed its first role as a main Support Base for future operations in Europe, and an Army Mobilisation Centre.
By 1943, 31 miles of track had been laid which was operated by 7 locomotives. The personnel of the BMR was formed of the Railway Operating and Maintenance Detachment of the Royal Engineers, which in 1943 consisted of 136 officers and men. The railway personnel resided at No. 3 Camp in Arncott, in poor conditions in overcrowded Nissen huts. Most of the BMR staff had been employed by the civilian railway lines. In addition to training on the Longmoor or Melbourne Military railways, the personnel also received basic military training in drill, weapons and explosives. 
The original BMR was considered an excellent achievement and a testament to the Corps of Railway Engineers, Royal Pioneer Corps, Royal Corps of Siganls, the 3rd Non-combatant Corps and the Italian PoW. The network was built quickly, and performed very well for a heavy loading job. 
The depot achieved its peak activity in the latter part of the war when some 20,000 troops and members of the ATS were employed there. Since then the depot has had a number of roles.
It was in 1961 that Central Ordnance Depot (COD) Bicester was selected to play a key role in a major reorganisation of the UK Base Ordnance Installations. The ordnance depots at Didcot and Branston, together with their associated “outstations”, were closed and their functions concentrated at Bicester.
Further reorganisation in 1980-82 led to the closure of other Depots – Chilwell and Ruddington (near Nottingham) – and the transfer of its stock holdings to Bicester and even more responsibilities.
The Garrison occupies an area of 12½ square miles. The storage area was initially dispersed to minimise the effect of conventional aerial bombing. The Garrison roads stretch over 32 miles and the Army railway has over 41 miles of track. The storage areas are enclosed by 21 square miles of perimeter fence.
In April 1999, the depot changed its name to Defence Storage and Distribution Centre (DSDC) Bicester.
In 2000, the Garrison had 850 servicemen and 2500 civilians working within its boundaries. They were the largest employer within Cherwell District Council. 
Bicester Garrison has responsibilities extending to Banbury in the north, Milton Keynes in the east and Oxford city in the south. The Bicester site occupies an area of some 12 square miles, this is primarily because of the storage depots which were spread out and dispersed to minimise the effects of conventional aerial bombing. The Garrison roads stretch over 32 miles and the Army railway has over 41 miles of track. The perimeter fence is 23 miles long round the storage areas, but the estate boundary is considerably more. 
As of 31st July 2018, Bicester Garrison lists the following units as being active on site:
HQ Bicester Garrison and Garrison Support Unit (HQ BG & BGSU)
23 Pioneer Regt RLC/1 CSL Regt RLC
DEMS Trg Regt
241 Signals Squadron – 10 Signal Regiment
299 Signals Squadron (SC) – Bletchley
Bicester Army Learning Centre 77 AEC
Logistic Commodities and Services (DES LCS)
262 Signal Squadron – 15th Signal Regiment (IS) – LogNEC (Fwd)
16 Cadet Training Team (CTT)
Defence Storage Group (DSG)
DES Log NEC PMG
142 Veh Sqn RLC – Banbury
710 Op Hygiene Sqn RLC – Aylesbury
Oxford University Officer Training Corp
Army recruiting Team
HQ Oxon/Bucks Cadet Force. 
Very recently (2018) the MOD has been selling off some of its estate and the Graven Hill Depot area of this site has now been turned over to housing which has inevitably resulted in the closure of lengths of the railway. The site of Graven Hill was an ordnance depot first used during World War Two and still in use in the early 21st Century. Arncott Hill and Graven Hill formed the focii of the vast site. Some areas of the site have fallen out of operational use. However, numerous storage hangars and much of the original infrastructure remain. It is the outstanding example in the UK of a bulk storage depot built during the Second World War, designed to be fully integrated into rail and road transport networks and is the precursor of the modern commercial distribution depots dotted around the motorway network. 
The Bicester site was divided into two main areas. The depots were named for the hills that they surround – Graven Hill Depot and Arncott Depot. The two depots were further sub-divided into six distinct functional sites, A, B, C, and F at Arncott, and D and E at Graven Hill.
Graven Hill Depot Railways
Completed in 1943, the depot at Graven Hill was operated by a mixture of soldiers, Auxiliary Territorial Service (ATS), and civilian staff; military personnel were originally housed in temporary Nissen huts, later to be replaced by permanent barrack blocks – St. David’s Barracks (completed 1958). The complex was served by the Bicester Military Railway, fed from the Oxford to Bletchley railway line. After 1945, COD Bicester remained the premier ordnance depot for the British Army, although since the 1960s, the functions associated with the different parts changed. The depot is now subject to disposal. . The site is shown below courtesy of an image from aeroengland.co.uk available on the internet. An aerial view of the Graven Hill Site taken in 1945. The connection to the national network can be seen on the top right of the image. An extract from the Ordnance Survey plan of the site taken from an archaeological report on the site which shows the general railway layout well. Graven Hill signal box can be picked out to the southwest side of the main line. The proposed housing development plans from 2015 leave the railway intact on the southwest side of the site. 
The Bicester Military Railway left the national network to the South of Bicester. The OpenStreetMap map below shows Bicester Village Railway Station and Bicester Outlet Village and to the south of these, Bicester Sewage Treatment Works and the network rail-side exchange sidings for Bicester Military Railway.Holding sidings at MOD Bicester. Wagons are brought into the holding sidings by main line locomotives. They are then taken onto the military railway by the MOD locomotive, (c) Steve Daniels. 
Access to the Military Base was from the south end of the exchange sidings above and is shown on the map below.The military base is shown as a light pink tinged area, surrounded by a red line. The railway entered it as it crossed Langford Lane, marked with a ‘x’ above and shown at the north-west corner of the satellite image below.A train enters the Bicester Miltary Railway site, (c) Steve Daniels. There was a complex network of sidings at the entry point to the Military railway. Graven Hill Signal Box viewed from the East was south east of the sidings shown on the map above.  It can be seen casting a long shadow in the bottom right-hand corner of the satellite image below.
Leaving Graven Hill Depot, the railway line approaches Ambrosden on the way to Arncott Depot.The first road encountered on the journey was crossed by a level crossing – Merton Road was crossed just to the West of Ambrosden.Looking north-west towards Graven Hill from Merton Road Level Crossing, Bicester Military Railway. Ambrosden platform was situated on the right hand side of the track. 28th March 2017, (c) Roger Marks.Merton Road west side gate, (c) John Grey Turner.Looking south-east towards Arncott from Merton Road Level Crossing, Bicester Military Railway. The building on the left once housed the crossing keeper. 28th March 2017, (c) Roger Marks.Merton Road Level Crossing at Ambrosden on the Bicester Military Railway. 28th March 2017, (c) Roger Marks.Merton Road ground frame, (c) John Grey Turner.
Just to the south of the River Ray the line enters the Arncott Depot. The depot boundary extends out towards the River Ray so as to encompass the multi-way points which opened out into the depot sidings and the signal box which can be seen towards the top of the satellite image below.Arncott Depot entrance gates and signal box, (c) Mark Edwards. The railway spreads out to serve a series of warehouses and operational buildings. Top centre to bottom right is the line which runs toward the now disused Piddington Depot which crossed Norris Road close to the also doused Arncott halt.
The next three pictures show the area immediately around the blue flag on the satellite image above, the road crossing and halt.The disused Arncott Main level crossing on the Bicester Military Railway, looking towards Arncott yard and Bicester. 12th September 2017, (c) Roger Marks.Arncott Halt before the track was lifted, this view looks towards the level crossing above, (c) 70023venus2009. The remains of Arncott station on a disused section of the Bicester Military Railway. 12th September 2017, this view is taken from the level crossing above, (c) Roger Marks.
The line to the Paddington Depot travelled to the south of Palmer Avenue to meet the B4011. The level-crossing on the B4011 is shown after removal of some of the line. Looking West towards Arncott with tracks in place. The view looking towards Arncott and the working part of the Bicester Military Railway, from the disused Piddington branch at Piddington crossing. The former crossing keeper’s hut is on the left. 12th September 2017, (c) Roger Marks.The view from the level crossing looking east towards Piddington Depot before the removal of the line. The disused Piddington branch of the Bicester Military Railway, looking towards the terminus from Piddington Crossing. 12th September 2017, (c) Roger Marks.
Returning to Arncott Depot. The map below shows the northern part of the Depot with the gate/signalbox at the top and the line to Piddington leaving the image on the right. The second map below shows the southern half of the depot and its connection across Murcott Road to St. George’s Barracks.The crossing at Murcott Raod is shown in the next few images.Murcott Road Crossing west side, (c) John Grey Turner.Murcott Road Crossing west side, (c) John Grey Turner.Murcott Road Crossing, (c) Steve Daniels.Murcott Road West, (c) John Grey Turner.This plan shows St. George’s Barracks and the link at the top right back up to the line to the Piddington Depot.
Locomotives and Rolling Stock
I have only been able to find a small number of pictures without all rights reserved. There are a variety of sources of photographs of the line and it rolling stock. One interesting set of photos are taken by Chris Turnbull on a Railway Study Association visit to the BMR.  A short, eclectic series of photographs follow below, some taken at Bicester, others elsewhere. The common thread is that locomotives and rolling stock once served on the BMR.D2700, 0-4-0DM built by the North British Locomotive Co.Ltd., Glasgow in 1955 No.27426. Originally numbered WD8205, it worked at Bicester, Marchwood and Longmoor Military Railways before passing into private ownership in the 1980’s. MoD No.01512 (ex-301) “Conductor”, a Thomas Hill (Vanguard) 34t 0-4-0 diesel hydraulic locomotive with 255 hp Rolls Royce C6SFL engine. On display at Long Marston Open Day in June 2009, from its home base of the Defence Storage & Distribution Centre, Bicester. Shunting loco “Storeman”, (c) Steve Daniels. The exchange sidings, with a coach and loco from the Bicester Military Railway © Ian Mortimer.BR Mk1 SO 4754 ex Bicester Military Railway, Horsted Keynes, 2 August 2014, (c) Nigel Menzies.Purchased from the Army’s Central Ordnance Depot Military Railway at Bicester, its TOPS classification is VJX. It was built as No. 23136. BR Box Van B784284 – B784284 was withdrawn from British Rail service in November 1984, going into Army service. It was purchased from the Army’s Bicester Central Ordinance Depot in October 2000, the Army’s number being WGB 4188. This van is fitted with instanter couplings, which are a later version of the three link, (c) Mark Cann. Looking through the boundary fence at MOD rolling stock, (c) David Luther Thomas. M.o.D. and ex railway company rolling stock at Bicester Depot. (c) David Luther Thomas. LSWR Goods Van (AD 47253) – Arriving at Quainton in August 1972 from the Ministry of Defence, Graven Hill, Bicester; this van carried the army number AD47253. It is fitted with a hand brake only. The 2-row carriage shed at the Bicester Military Railway, June 2007. 
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