In June 1939, the company based at Morley was split off to form the cadre for a duplicate unit, the 51st (Leeds Rifles) Battalion, Royal Tank Regiment.

[5] There were almost no armoured fighting vehicles available for the TA regiments, and the few possessed by 45 RTR were deployed for airfield defence in North East England during the Battle of Britain.

[7][8] In May 1942, 45 RTR embarked at Liverpool for the Middle East, sailing round the Cape and reaching Egypt in July.

At the end of the day, 45 RTR handed its remaining tanks over to other regiments and was withdrawn into reserve.

Nevertheless, on 8 March 1943, 45 RTR was finally disbanded and replaced by a Royal Armoured Corps holding unit.

[14] When the Territorial Army was reformed after the war, it included a combined 45th/51st (Leeds Rifles) RTR.

It carried the honorary distinction on its colours and appointments of the badge of the Royal Tank Regiment with dates '1942-45' and two scrolls inscribed 'North Africa' and 'Italy' (51 RTR fought in the Italian Campaign).