Both Hekety (Sheffield-based) and The Gloworms (London-based) have already done South Bank ceilidhs outside the National Theatre - with Gordon Potts calling. And there really is no other band like Glory Strokes. Of others mentioned, I'd certainly endorse Stômp and Climax Ceilidh band, both of which are based in London.

It comes down to who's available - and time's getting on.