Flew back from BOS coach last week (my dime, "short" flight for me) and was upgraded to WT+ at bag-drop "check-in" (I had used OLCI to get a better seat).

Ate a decent meal and then went to the lounge (BA Silver) and fought for a seat. At the gate, I was upgraded again to CW. Very surprised. The flight was quite full, if not totally full (didn't go all the way back to check :-)

While I have lots of miles on BA, much of it is zero-tier-points cheap ticket stuff, so I am not likely to have been singled out for my high value to BA.

BTW - I also always request a low-fat meal. This normally follows me pretty well around the airplane, although even sitting in a preassigned seat, some cabin crew seem capable of screwing it up (Hint - want a special meal? Just raise your hand - the FA is dying to offload it on anyone.) Anyway, on this occasion, my low-fat meal didn't make it to CW.