Collett 57' Coaches
As part of Charles Collett's coach improvement programme, between 1927 and 1929 fifty-six non-corridor vehicles were built to the D98 Brake Third and E131 Composite diagrams and fitted with 7ft Bogies. Each type was built in two Lots; 1376 and 1388 for the Composites and 1377 and 1389 for the Brake Thirds, forming twenty-eight 4-car sets that were initially allocated to Birmingham, London and Chester.
By 1937, the 4-car Sets on the Birmingham Division became officially classified as 'B Sets', being formed up as Brake-Comp-Comp-Brake. Over time this led to confusion with the West Country 'B Sets'. which were formed of two Brake Composites but in the Midlands areas these two car sets were classified as 'D Sets'. The working of the 'B' Sets in the Midlands area was extremely complex and involved the Sets being spread across the division overnight, ready for operation the next morning. Like the heavier 'A' Sets, the 'B' Sets could be strengthened for peak services by adding loose coaches or an additional set. Sets could sometimes even be used on excursion duties, as photographed in 1937 in the Bournemouth area but this was a rare occurrence caused by shortages of corridor stock.
Following the Second World War, some of the Sets were dispersed and disbanded, while others were formed into 3-car Sets from 1954/55 onwards, the addition of a Third Class vehicle to the Composite and Brake Third coaches. This period marked the beginning of withdrawals and scrapping of the type was completed by 1962.