Class 157 was the designation applied to a range of Diesel multiple unit trains of the Sprinter family planned for regional use, in particular for the Strathclyde Passenger Transport Executive. As well as the class number, British Rail reserved carriage numbers in the 526xx and 576xx series for these units.As the privatisation of British Rail began, this project became unviable, and Strathclyde ended up receiving a batch of Class 170 units.