Hovis,
I understand from a CAA surveyor pal of mine that they are bogged down with B licence conversion applications at the moment.
Also, they do accept that many limited authorisations will satisfy the requirements for the issue of an A licence but it is not a priority for the CAA at this present time.
I know this does not appear to help the guys at BA who need confirmation asap but I also understand that the subject has become a hot topic between the airlines and the CAA at this time.