I am not celiac but only suffer from wheat allergies. But in such circumstances, I have to order the GFML and I find that LHR catering is one of the worst when it comes to as described by people above, tasteless.

It usually isn't the airline's fault but rather the catering arm which is not owned by the airline that makes the dishes. I also like butter and dairy, but why do GFML always omit those?

I find the following catering stations have very good GFML meals, however my experience has almost always been on CX flights.

HKG
BKK -especially the bread. Yummy!
KUL
ZRH
SFO

The rest are a hit and miss! Yes crew have to be trained that some of us have severe reactions to gluten - just as those who are allergic to nuts.