Prior to 1897 general service corridor carriages were 45ft
(or occasionally 42ft) long. Between 1897 and 1903 50ft became the normal length. From 1903
the carriage length was stretched to 57ft, though some composites 52ft 6in long were built
from 1910. The longest full brakes were generally of 50ft, though some 57ft vehicles were
converted to full brakes after 1918.
For LNWR carriages, the transition from the arc-roof to the cove-roof style came during the 50ft era and that from cove roofs to high elliptical roofs during the 57ft era. The WCJS style changed from arc to elliptical roof without any intervening cove-roof stage.The top-light style was introduced from 1911.
The earliest dining cars of 1893 were of several different lengths; those built for “The Corridor” (WCJS vehicles) were of 45ft; others were 47ft 9in and 50ft 6in long. Some of these had entrance vestibules at only one end. From 1895 the length was standardised at 65ft 6in, though the very last pre-grouping LNWR diners were 68ft long. Clerestory roofs were usual for both LNWR and WCJS diners until 1907, when elliptical roofs came in for LNWR diners; no WCJS diners were built with elliptical roofs.
The first LNWR and WCJS sleeping cars were 65ft 6in long, built with clerestory roofs until 1907 when elliptical roofs became the norm. In 1914 the length was increased to 68ft 0in and this became the standard until (and after) the grouping.
Sleeping composites were all 50ft long; those of 1906 clerestory roofed and those of 1907 with elliptical roofs.