In the domestic lounge at LHR T1 recently, I became aware of some incredibly loud snoring after sitting down. I looked around several times to see if I could locate the offender and move myself but there was no obvious sleeper to move away from. On a trip to the bar I came to the conclusion that the snoring noise was coming from an area where everyone was awake and as such one of them must have had a health issue. It really was like a foghorn at times.