At the start of the great war the war department (WD) chose the nearly redundant warehousing at the head of the  Twa Dale canal as a supplies & repair depot  for the newly formed Royal Flying Corps. The presence of a good level area of land (airfield) adjacent seems to have outweighed the impracticalities of the site.

It soon became clear the canal was in very poor condition and unable to cope with the volume of traffic required for the building program. The contractors got permission to lay a narrow gauge railway (mainly along the tow paths) to the railway at Cents some 8.5 miles away. The route though was some 12 miles due to the need to circumvent Letts bluff through which the canal was tunnelled.

The success of this temporary contractor’s line led to the closure of the canal. The Railway was re routed through the canal tunnel at Letts bluff cutting 3.5 miles and a savage gradient, off the route. The basin at Twa dale was filled in and used for further buildings.

It is now 1929 (ish) the facilities are owned by Twa Dale Estates who have encouraged a large number of small engineering and furniture manufacturers into the site and operate the railway. Some of the original contractor’s vertical boiler locos are still in service along with ex wd types and some later acquisitions. As any keen geographer would know the Cents Lets and Twa dale railway  ( pronounced in the local accent as senseless an twaddle railway) is situated in the small county of fiction which shares borders with both reality and fantasy.