If you have Foursquare look at the comments for BA GF T3. There's comments going back to at least 2011 saying there's no hot buffet.

Even when Compass offered an edible buffet it wasn't available during quiet periods.

Why would you want the BaxterSlurry trays when you can order off the menu?

BTW another poster on here gets Avios compensation each time he mentions to customer relations that there's no hot buffet! No one outside of the people who run the T3 lounge seem to know whether it's supposed to be offered or not.

I've never tried getting avios for the lack of buffet. Don't want them to think the buffet is something I really want.