Simplex 40SD 529 of 1984 was the last loco to be built at Simplex's Elstow Works at Bedford, as later locos were built under license by Alan Keef before he finally bought the company.
It spent the whole of its working life at Severn Trent Water"s Stoke Bardolph Water Reclamation Works, Sewage Works in plain speak, where it was used to move skips full of "solids" from the filter beds, to the tipping site. As far as can be ascertained it last worked in September 1994.
It is powered by a 3 cylinder Deutz air cooled engine, which means that the characteristic radiator is missing, the "bonnet" of the loco extending forwards to the front buffer beam.
Compared to earlier Simplexes, this loco is considerably shorter. It has a car like "pull on" handbrake instead of the more normal wheel type. This makes the loco short enough to be packed across a standard ISO container.
This also means that the cab is considerably more cramped. The cab was removed at the sewage works, because it was considered by the staff to have insufficient emergency exit to cater for the locomotive rolling over and trapping the driver inside. A new wider cab has been installed on the loco, followed by airbraking to passenger hauling standards. The loco is now used on short formation trains on quieter days of passenger carrying.