From left: Class 37 locomotive (1965) — for south Wales local services from next month; InterCity 125 (1976-82) — 26 being transferred to Scotland after withdrawal from Great Western; Class 442 Wessex Electrics (1988) — 18 being reintroduced on South Western Railway from next month, but delayed

Rail users face fresh chaos after the late delivery of new trains and the forced withdrawal of older ones leave operators without enough to run a service.

One company is hiring 54-year-old locomotives hauling 1970s coaches to cope with the crisis. Others are using mothballed trains from the 1980s. Some are having to cut services by up to half.

The unpopular Pacer units, which ministers promised to scrap by the end of this year, may also have to be kept running to handle the emergency. Built with a body designed for buses, they were meant as 20-year stopgaps but have been in use for almost twice that long.

Roger Ford, industry and technology editor at Modern Railways magazine, said: “It is a very serious problem.