The Mk1 was BR’s first standardised design of railway carriage with thousands built across BR’s carriage works in Derby, Wolverton, Doncaster, York, Eastleigh, and Swindon between 1951 and 1963. Later examples utilised a Swindon-designed ‘B4’ bogie which gave a much-improved ride and was adopted for use on Southern Region Mk1 Electric Multiple Units (EMUs).
