The sole question for EC 261/2004 purposes will be whether the delay into LHR was caused by an "extraordinary circumstance." The rest of this is supposition and irrelevant because OP would not have been permitted through conformance at Flight Connections with a BP in any event.

It will be for BA to prove that there was an ATC "restriction" causing the 22 minute delay and thus roughly 18 hour delay into EDI, the final ticketed destination. But, if BA can do so, the EC 261/2004 delay claim should be denied (as well as an IDB claim presuming that one accepts that conformance is reasonable).

I trust that BA did pay for the hotel and meals as that is due under the Regulation no matter the reason.