Having eight-coupled wheels of 5' 1" diameter, they were clearly intended mainly for hump shunting duties. Although they were tried out on other duties around the system, most of their life was spent allocated to the new shed at Feltham. They were massive locomotives, weighing in at 95 tons and were by far the most powerful locomotives on the LSWR. In early SR days, Maunsell gave consideration to building more locomotives to this design, but decided instead to develop his Z class 0-8-0T, so the G16 class remained numerically small at only four. Originally it had been intended to use them for transfer and trip workings so superheating was provided. Originally, of course, these were the Eastleigh design of superheater, but in later years these were replaced by the Maunsell pattern. This turned out to be a hindrance to the shunting activities and most of the transfer and trip workings were assigned to the similar H16 class of 4-6-2 tanks. The G16 and H16 classes shared many components of the same design, such as boilers and fireboxes. The G16s, along with the T14s and H16s, were the widest steam locomotives in Britain.

The lack of maintenance for most locomotives during WWII meant that such massive and reliable machines as the G16s continued their hard work even in very run-down condition. Inevitably, the introduction of the ubiquitous 0-6-0 diesel electric shunters at Feltham in the 1950s made the G16s redundant. They were used occasionally on empty stock and van trains, from various depots such as Guildford, but these duties were limited in numbers and further electrification in the Southern Region meant that there was a surplus of locomotives in the late 1950s. One G16 was withdrawn in 1959, another in 1960 and the final two in December 1962. None has been preserved.