Don't forget that at the time we're talking about (mid-50's) the backbone of Transport Command was the Hastings which could carry approx 50 troops, but were relatively slow, and the standard way of moving servicemen was the troopship. Therefore moving battalions required a lot of aircraft if the troops were needed in a hurry (like most MOD plans!) so other fleets, Shackletons, Varsities, Valettas etc were pulled in to the mix!