The class was originally numbered 687–716 but the year after delivery numbers 702–716 were given new numbers vacated by engines that had been withdrawn. The locomotives gained the nickname 'Black Motor' early in their career. They were well designed and had few major modifications during the existence of the fleet – the exception being fitted with superheaters from 1919 to 1929, which required the fitting of an extended smokebox. They shared many standard parts with Drummond's other designs (including sharing boilers with the M7 class).
Nos. 702–716 were renumbered by the LSWR between June and August 1898, becoming 306, 308, 309, 315, 317, 325–327, 339, 346, 350, 352, 355, 368, 459 respectively. In June 1912, no. 459 was renumbered again, to 316.
Soon after the locomotives passed to Southern Railway (SR) ownership, their LSWR numbers were prefixed "E" to denote Eastleigh Works - this was done to distinguish similarly-numbered locomotives from the other constituents of the SR; thus, LSWR no. 687 became SR no. E687. These prefixes were dropped from mid-1931. In the meantime, there had been a proposal (prepared in March 1927) to renumber some classes into continuous blocks: the 700 class were allocated the series E336–9, E369–379 and E686–701 but none were actually renumbered, and the plan was cancelled in December 1927.
The first to be withdrawn was No. 30688 in September 1957, with the second, No. 30352, following in June 1959 and then the 3rd, No. 30687, in September 1960. The final seven were all withdrawn by British Railways in December 1962.