26043 was one of a class of 47 locomotives built by the Birmingham Railway & Carriage Works in Smethwick, entering service in October 1959 numbered D5343 and painted in all over BR green livery with white waist level stripe and white window surrounds.
The loco weighs 75 tons and its Sulzer 6 cylinder 6LDA28 power unit develops 1160hp. An erstwhile Scottish locomotive, initially it was allocated to Haymarket depot and during its career spent periods at Dundee and Eastfield. However for the largest part of its working life it was allocated to Inverness depot, operating passenger and freight services over the far north lines to Wick, Thurso and Kyle of Lochalsh.
In January 1974, D5343, by now painted in BR blue livery, was renumbered 26043 under the TOPS (Total Operations Processing System) scheme. Then in May 1985 it received a Heavy General Overhaul and lost its steam heating boiler and water tanks in favour of air brakes and associated equipment.
The next few years were spent officially as a freight only machine and in 1990 it was painted in the Civil Engineers livery of ‘dutch’ grey and yellow. During January 1993, whilst allocated to snow clearance duties between Perth and Blair Atholl, 26043 suffered a power earth fault. Repairs were not authorised and it was withdrawn on 19th January 1993. Initially stored at Perth, it was then moved to MC Metals in Glasgow for asbestos insulation removal, which entailed major dismantling of the cab interiors. The loco was then purchased by the Cotswold Mainline Diesel Group in late 1993 and it arrived at Toddington in April 1994.