i would be cautious and check what is shows on ba.com when you come to book it. usually a domestic flight when booked connecting to/from long haul WTP will book in K selling class which is economy.

having said that, if you were in business for EDI-LHR you would get access at EDI, but no access at LHR. and on the return, you get no access at DEL, but you will get access at LHR if your LHR-EDI is in business.