The six locomotives that comprised the Taff V class were introduced in 1899 as replacements for earlier non standard designs. Numbers 75, 80 and 90 were delivered in the May of that year, with 91, 99 and 100 following in the next month.
When new, they were fully lined out, with the saddle tank divided into two panels by the white, yellow and red livery, together with the cabsides and bunker. The splashers had brass beading around the circumference, but it is not known how long this elaborate livery would have been continued.
They remained unaltered up until the grouping, when they were renumbered 788-791, and 786, 787 respectively. In 1923 to 1925, three were fitted with new boilers, and two others given overhauled ones, and at the same time, a small portion of the front of the saddle tank was cut away to give better access for oiling the inside motion. Only 787 was left untouched, and was the first to be sold in 1926, the others were sold out of service between 1927 and 1930. No.791 was sold to Hatfield Main colliery and continued to work until 1963, when it was scrapped in the March of that year. The four other locos were sold to GKN Dowlais (786/787/788), and the Blaendare Co., Pontypool (789). No.790 did not find a buyer and was scrapped at Swindon sometime after 1928.