Well, that was pretty horrible.

BA274 eventually took off around 02:00 from LAS, landing about 19:50 at LHR.

Technical problem on the way out on BA275 re-occurred on the return: basically broken heating / aircon. The back of Y was a sauna and WTP (where I was) was an icebox. Shivered for 10hrs with 2 blankets & pairs of socks. Crew very apologetic & pilot said on landing that the plane was going straight to the hangar, but definitely not one of my favourite BA flying experiences.