The London and South Western Railway (LSWR) employed the use of block trains on many of its suburban routes during the 19th century. By the end of the century, many block trains were comprised of old fashioned stock compared to the new mainline vehicles that were coming into service. In January 1900, it was agreed to replace some of the old block trains. Thus produced were a new set of 6 wheeled carriages which were similar to the elliptical roofed mainline bogie vehicles. Each train was to consist of four Firsts, two Seconds, two Composites, four Thirds, and two Brake Thirds. In this case, unlike most stock up until that time, the Composites had Third and Second class compartments, rather than the usual Second and First class. The trains were fitted with electric lighting. In 1901, it was decided to withdraw more old block train vehicles and replace them with two more 14-coach block trains. Then, in late 1901, it was decided to build another two sets, but with 13 coaches this time.
Although the coaches were ordered and built as six 14-car and two 13-car trains, they were commonly run as sets of 13 coaches. The coaches were mostly close-coupled. Since the coaches were electrically lit, there was little reason to go onto the roofs (and very little room between the coaches due to the 1ft 2in spacing between coaches), so steps were only provided on the Brake Third coaches.