(Photos 3-5 © Ian Leach, photo 9 © Rick Johnson)
The Portpatrick & Wigtownshire Joint Railway, often known as the Port Road, linked Stranraer to Castle Douglas where it made an end-on connection with a line to Dumfries. It was authorised by an Act of Parliament in August 1857 and opened in March 1861.
In remote countryside to the north of Gatehouse, the route spanned Big Water of Fleet by means of a 300-yard viaduct. Each of its 20 segmental arches comprise six courses of brick whilst the spandrels are in stone. 1940 saw the piers strengthened with brick encasings and the two sides of the structure tied together using bullhead rail and connecting rods beneath the arches.
During the Second World War, the port of Cairnryan was purpose-built as No.2 Military Port with three harbour piers and a railway linking it with Stranraer. Millions of tonnes of ordnance and supplies came into the UK, much of it being transported over the viaduct. Then, in 1943, the railway also helped to move US troops.
The line failed to survive the Beeching cuts, closing on 14th June 1965. The viaduct's smaller 9-arch sister - Little Water of Fleet - was blown up by the Army as part of a training exercise.
In 1935, Big reputedly starred in Alfred Hitchcock's film version of John Buchan's thriller 'The 39 Steps'. It also made an appearance in 'Five Red Herrings', a 1975 TV outing for Lord Peter Wimsey. It is hoped that it will eventually play host to an official footpath.
(Many thanks to Michael King for much of the above information)
(Rick Johnson's photo is used under this Creative Commons licence.)