The idea of British soldiers using American tanks was not viewed with a great deal of enthusiasm by the British Army.
They perceived American tanks as being crudely made, mechanically unsophisticated and impossible to fight in.
However, once British crews got used to them and learned to cope with some of their difficulties, such as limited fuel capacity and unfamiliar fighting techniques, they started to see them in a far more positive light, in particular their innate reliability and simp.
Osprey Publishing (uk) British battle tanks: american-made world war ii tanks, hardcover/david fletcher
