A lot of acting courses do train their students in some musical theatre as well (indeed, at my drama school, on the acting course they have singing lessons every year, singing as part of the showcase and often a musical is part of the final year performance schedule). It's all about being versatile in the theatre industry and acting courses realise this. There are certainly plenty of working performers in musical theatre who trained at Guildhall.
And my information comes from professionals in the MT industry. Francesca's list looks a bit more like it from all accounts, though, as I say, the NCDT courses are all of a certain standard and entry on to any of them is an impressive achievement. Wherever you go though isn't going to guarantee you a career in this business.
Incidentally, I've been very impressed by students coming out of the MT postgrad at RSAMD, though I assume this thread has a more undergrad focus.