The first 20 locomotives were built with 7 ft 1 in driving wheels and were designated class X2, but upon their completion Adams introduced a class of very similar locomotives, the T3 class, with longer smokeboxes, smaller bogies wheels and driving wheels with a reduced diameter of 6ft 7ins. Adams chose the smaller sized wheels as the locomotives were intended for use on the undulating lines west of Salisbury. However, upon completion of the class by 1893, some were sent to major depots on the Bournemouth line, as well as those on the Salisbury-Exeter route.

Drummond gradually replaced the elegant stovepipe chimneys with one of his own design, but as these and other minor modifications took place under Drummond's care, the T3s were being displaced by more modern designs such as his T9 class. A few T3s were sent west of Exeter where they were particularly successful. During the First World War, these T3s, like all of Adams locomotives, were in much demand and all survived to be taken into Southern Railway stock in 1923.

With the spread of electrification in the 1920s and 1930s, a surplus of light passenger locomotives on the LSWR and SR was building up and withdrawals of the T3s commenced, with all but three going by the end of 1933. One of the remaining three was withdrawn in 1936, but numbers 563 and 571 saw the start of World War II. However, N°571 was withdrawn in 1942 having amassed more than 1.7 million miles in service. N°563 continued in service only to be laid aside in 1945 with over 1.5 million miles in service. It joined the ranks of locomotives outside the works at Eastleigh awaiting the torch, but preparations for the centenary of Waterloo station were under way for 1948 and N°563 was chosen to represent the old London & South Western Railway. It was partially restored and painted in the early Drummond livery of the LSWR

On the closing of the exhibition, N°563, together with other exhibits, was stored at the back of Farnham electric carriage shed. In 1958 it was transferred to Tweedmouth for storage until the 'permanent' home of the BTC Museum at Clapham was established. In due course, this was closed and N°563 was sent to the new National Railway Museum at York, where it was on permanent display in Drummond's 1903 livery until 2017. In March of that year the National Railway Museum generously gifted the N°563 to the Swanage Railway Trust which set about returning her to steam.

An extensive strip down and investigation at the Flour Mill workshop in the Forest of Dean showed that the engine was in a surprisingly good mechanical condition, although the firebox was life expired. After six years and some half a million pounds the engine returned to steam at the Swanage Railway on 22nd September 2023 where, after due checks and any necessary fettling, she is due to return to revenue earning trains on 8th October 2023.