The class 142 were built by:

British Rail Engineering Limited at Derby Litchurch Lane Works
Leyland Bus

The body for the pacers were made by Layland Bus part of the project with them using bus body's for the pacers as there was less bus journeys but more on the railway so British Rail and Layland came up with the idea for the pacer.

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Excessive flange squeal on tight curves has been a problem on many routes operated by 142s caused by the long wheelbase and lack of bogies. The rough ride which can result has led to the units being nicknamed (along with the related Class 143s) Nodding Donkey.

The 142s that were (briefly) allocated to Cornwall, in the mid-1980s, were officially known as "Skippers". They were transferred to the north when the Cornish branch lines proved unsuitable for the Class 142, the tight bends caused excessive screeching and caused the wheels to become damaged, all skippers left the West country in the late 1980's.

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