) ▁which ▁was ▁already ▁in ▁British ▁service . ▁ ▁British ▁experience ▁of ▁the ▁ 3 7 mm ▁gun ▁had ▁been ▁under wh el ming , ▁and ▁the ▁M 2 ▁medium ▁was ▁turned ▁down . ▁ ▁The ▁next ▁version , ▁M 3 ▁medium ▁( l ater ▁known ▁as ▁Lee / Gr ant ) ▁was ▁already ▁part ▁way ▁through ▁design ▁and ▁had ▁a ▁tur ret ▁too ▁small ▁for ▁the ▁larger ▁ 7 5 mm ▁gun . ▁ ▁To ▁meet ▁British ▁requirements , ▁the ▁design ▁was ▁modified ▁to ▁add ▁a ▁larger ▁gun ▁in ▁a ▁side ▁spons on . ▁ ▁British ▁needs ▁were ▁then ▁added ▁to ▁the ▁M 4 ▁medium ▁( Sh erman ) ▁requirements . ▁ ▁Both ▁t anks ▁were ▁produced ▁in ▁greater ▁numbers , ▁and ▁Sh erman ▁gained ▁the ▁uno fficial ▁mon iker ▁" he avy ▁cru iser ". ▁ ▁The ▁t anks ▁that ▁received ▁the ▁names ▁Caval ier , ▁Cent aur ▁and ▁C rom well ▁were ▁all ▁designs ▁to ▁meet ▁the ▁same ▁requirement ▁for ▁a ▁cru iser ▁tank ▁to ▁replace ▁the ▁Cr us ader ▁tank . ▁Design ▁work ▁took ▁place ▁in ▁ 1 9 4 1 ▁and ▁ 1 9 4 2 , ▁foc uss ed ▁primarily ▁on ▁develop ments ▁in ▁engine ▁and ▁transmission ▁techn ologies . ▁The ▁A 2 4 ▁Caval ier ▁and ▁A 2 7 L ▁Cent aur ▁used ▁the ▁N uff ield ▁Liber ty ▁engine ▁while ▁A 2 7 M ▁C rom well ▁used ▁the ▁more ▁powerful ▁Roll s - Ro y ce ▁Meteor . ▁ ▁When ▁US ▁t anks ▁entered