I flew EDI-STN and back last weekend. On the outbound at EDI, the person checking Boarding Passes at Security didn't ask for my passport, but just scanned the barcode on my Boarding Pass in her computer and let me go. Same thing on the inbound - I actually handed my passport to the security checker at Stansted out of habit, but he just handed it right back before scanning the Boarding Pass and letting me through to the metal detectors without looking at the picture.
The airline did check my ID at the gate (multiple times at Stansted actually), and I suppose it doesn't really matter who I am so long as I clear security in the normal way. Still, it seems odd that they'd suddenly stop checking ID - the last time I flew a domestic UK flight, from LHR-EDI, security definitely checked my passport against my ticket. Is there a new policy against checking ID on domestic UK flights except by airlines? Or indeed anyone's ID? It didn't look like anybody's ID was being checked ahead of me, and I doubt they were all on Domestic Flights. Or was BAA just being lazy this weekend?