The 1973 Railway World Annual carried a one page article about the short railway on Alderney which was owned by the Department of the Environment and which served a quarry. 
The Alderney Railway opened in 1847 and ran for about 2 miles (3.2 km), mostly following a coastal route, from Braye Road to Mannez Quarry and Lighthouse. Wikipedia notes that: “The railway was built by the British Government in the 1840s and opened in 1847.”  It was built as standard-gauge track. 
On 8th August 1854, the Queen Victoria and Prince Albert rode on the railway in a horse drawn tender.The line’s “original purpose was to carry stone from the eastern end of the island to build the breakwater and the Victorian era forts.”  It was operated by the Admiralty and so was probably the first nationalized railway in the British Isles?  It carried stone for around 130 years. From the 1920s it was in private hands and crushed stone was taken off-island for road-building until the Second World War. 
During the War, under German occupation, no effort was made to maintain the breakwater. The standard-gauge track was replaced by German 60cm gauge rails and the line was used for the transport of munitions.
As we have noted its primary function was providing stone for the building of Alderney’s Breakwater. There bis an excellent article about this, written by M. Swift, in the Industrial Railway Society Journal, “The Industrial Railway Record,” No. 52 (February 1974) – p170-173. 
M. Swift notes: “The vast increase in maritime trade during the early Victorian period was followed by a demand for harbours of refuge around Britain, and the Government proposed several schemes during 1846‑47. One was for a breakwater some 2,650 feet long from Grosnez Point, on the north side of Alderney in the Channel Islands, enclosing 67 acres of water. This was developed by successive Admiralty Boards during 1854‑58, the final proposal being a west breakwater 6,600 feet long and an east breakwater from Chateau a I’Etoc, 1,700 feet long enclosing 150 acres. The cost was estimated at £2½ million pounds.” 
“The breakwater was planned as a rubble bank built up to 12 feet below low water, topped by a masonry wall with the promenade level on the sea side 37 feet above low water, and the quay level on the harbour side 23 feet above low water. The scale of the task was magnified by the depth of the water, which reached a depth of some 150ft.” Alderney Breakwater (Google Earth)The view Southwest along the breakwater towards Fort Grosnez (Google Maps). The old breakwater railway can just be picked out running from the bottom right towards the fort.A clearer image of the rails in the top surface of the breakwater. The picture is taken from further to the Northeast along the breakwater (Google Earth).
M. Swift describes the construction work in some detail. This is not directly relevant to this article but can be found by following the link in the references below. 
“The railway from the breakwater to Mannez quarries was 2½ miles long, laid to standard gauge with 65lb double-headed rails. A branch ran about half a mile to Craby Bay where shingle was excavated for making concrete blocks. The first two locomotives were six coupled with four wheel tenders, named ‘Veteran’ and ‘Fairfield’. These were replaced by two six coupled tank locomotives ‘Bee’ and ‘Spider’, and a four coupled tank locomotive ‘Waverley’ built by Henry Hughes of Loughborough. 300 to 400 four wheel 5‑ton capacity end tipping wagons were used to carry stone over the railway, and a few survived at least into the 1920’s.” 
The Industrial Railway Record (IRR)  includes a photograph of one of the locomotives used on the line. The Henry Hughes locomotive (Waverley) used by Thomas Jackson (the Contractor) in building the breakwater was later photographed on Alderney, presumably in Mannez Quarry when it was used to pull trains of stone in connection with the maintenance of the breakwater. The picture is included in the IRR article courtesy Ian Allan Ltd. 
The Alderney Railwat website has a photograph of one of the two 0-6-0 ST locomotives with the train of low stone wagons at the head of a page about the railway’s history. This photograph was also taken at Mannez Quarry. 
After the Second World War, “the Ministry of Defence re-laid the track at standard gauge (56½” – 1.435m) with concrete sleepers in panels and used ‘Molly’ a four wheeled Sentinel vertical boiler engine and rolling stock of 24 side tipping wagons (‘Yankees’) to tip Granite chippings into the sea from the Breakwater for maintenance of the mound.” 
The railway was probably in this form when it became the subject of the short article in The 1973 Railway World Annual. It was not long after this that negotiations were opened between the Home Office and the Alderney Railway Society which was formally established in 1978. ……Vulcan Drewry 0-4-0 diesel locomotive Elizabeth and former London Underground 1959 Tube Stock cars, (c) Dmartin@ukonline.co.uk (2007), (GNU Free Documentation License). 
In the mid 1970’s The British Home Office who were responsible for maintenance and operation, (there being only a minimal use of the track at this time), were approached to see if the line could be used for Passenger transport and after several years permission was obtained. Alderney Railway Society was established in 1978. When trains began to run in 1979, Alderney Railway Company Ltd was formed to hold the lease and operate the line. 
Passenger trains first ran in 1980.  Trip Advisor tells us that, for a time, the passenger railway ran under steam power(as illustrated on the postage stamp earlier in this article:
In 1982 an 0-4-0 Bagnall steam locomotive by the name of “J.T. Daly” was acquired and ran with two ex-Chatham Dockyard open wagons which had light weight roofs to provide some protection for the passengers. J.T. Daly remained with the Alderney Railway until the early 1990s but due to its limited use and high cost of maintenance was subsequently sold to the Pallot Steam Museum in Jersey.
1985 saw the arrival of the Vulcan Drewry 0-4-0 diesel locomotive “Elizabeth” which after 20 years is still providing sterling service. By 1987 it was decided to try and provide improved accommodation for passengers and two ex London Underground 1938 tube cars were acquired from the North Downs Railway. These were drawn and propelled by Elizabeth and gave good service but by 2000 both vehicles had unfortunately succumbed to corrosion caused by the salt sea air. They were returned to England and scrapped.
In 2001 the Alderney Railway acquired two replacement 1959 tube cars from London Underground numbered 1044 and 1045. These vehicles have aluminum bodies with wooden floors and hopefully will survive the salt air. 
Wikipedia tells us that the current stock includes the two London Underground carriages, two 0-4-0 diesel locomotives and six Wickham 27A MkIII railcars. [2, c.f. 10]
The first length of the historic line ran along the breakwater, then in front of Fort Grosnez before entering Braye Village. The passenger line running in the 21st century starts from Braye Road Station and heads East to Mannez Quarry.The old railway was in use out onto the breakwater. It can still be seen on satellite images. A short stub siding ran in the yard in the bottom left of this image. The route to Mannez Quarry curved South from the breakwater, (Google Earth).As it passed the East aspect of the fort, it divided into two to allow shunting of wagons (Google Earth).
The railway is open, Covid-19 permitting, as a tourist attraction, “nowadays, the old train wagons have been replaced by two London Underground carriages and a diesel engine carrying visitors from Braye Road Station to Mannez Station near the Lighthouse.” The line from the breakwater enters on the right of this picture. The station building at Braye Road Station is the timber shed to the left of centre. (Google Streetview).Tube stock stabled at Braye Road Station, (c) Dmartin@ukonline.co.uk (2007), (GNU Free Documentation License). 
- Michael Bryan; Alderney’s Railway; in A. Williams; Railway World Annual; Ian Allan, Sheperton, Surrey, 1973, p89.
- https://en.wikipedia.org/wiki/Alderney_Railway, accessed on 6th July 2020.
- https://www.visitalderney.com/see-do/things-to-do/alderney-railway, accessed on 6th July 2020.
- https://www.alderneyrailway.gg/railway-history, access on 6th July 2020.
- https://www.irsociety.co.uk/Archives/52/Alderney.htm, accessed on 6th July 2020.
- https://www.flickr.com/photos/moogiemedia/6255851446, accessed on 7th July 2020.
- https://www.flickr.com/photos/neilsingapore/3567378586/in/photolist-6reKnm-87AmaZ-VyTi9h-dLeVRF-fuZF3v-cdXh1d-6rz17G-ouCErL-9JQLfz-FUE3D1-w6Zf16-9tKisi-pYB9P2-dQbFN-26kYJNq-231nCkP-sxWm3d-2iJRV1S-JQ5C2x-7dKYBY-87oDAq-wYcvMA-u3TEQB-awL9Rn-qSrvmd-awL9FD-awNSFG-edfjGK-oeFp1e-owhLjY-by4Zx2-wYf47r-xhmmXZ-zohqyu-xFZFg5-cqasAS-xrLPUk-ow8paj-d5Y36Y-d5Y2Do-AyBsp-o7Ui7T-9tN6y3-xzvuXk-edm1zE-edfnCX-edfnTV-edm9uf-edm2nA-edm2Eo, accessed on 7th July 2020.
- https://www.jandrstamps.com/products/guernsey-alderney-1983-93-j-t-daly-steam-loco-24p-mnh-sg-a12d-tourism-railways, accessed on 7th July 2020.
- https://www.tripadvisor.co.uk/ShowUserReviews-g186228-d194222-r589431031-Alderney_Railroad-Alderney_Channel_Islands.html, accessed on 7th July 2020.
- https://www.ontrackplant.com/otp/9022, accessed on 13th July 2020.