My Dad's Little Boy,
Sorry old chap, but you're wrong on all counts there. As Tim states, there was never any official designation of B2A. All Vulcan B2's were just that, with the only differing designations being the B2MRR and K2 Tankers. This is borne out by every piece of official literature I have seen referring only to 'Vulcan B2' or 'Vulcan B2 Blue Steel'
The Blue Steels modifications were extensive, involving major Spar modifications required to recess the missile into the bomb bay. Therefore, only those airframes modified to carry Blue Steel could carry Blue Steel.
Tim,
Regarding the Retro-fitment of 301's, XH557 was initially delivered with 201's but was then used by Bristol Siddeley for engine trials, having first 2 x 301's in the No 1 and 4 position, later being fitted with 4 x 301's.
Flipflopman