I walked away whilst drafting my response and by the time I actually posted few extra comments have appeared, also mentioning the Flagship Lounge, glad I was not the only one to point this out.

For me, aside of being a very nice environment (MIA) , with large spaces, fairly good food (they even had a roast beef corner), the champagne offer would have already made it much better than BA Gallery Lounges: Piper Heidsieck, one of the best quality/value champagne out there (especially bought at £16/18 during the UK Supermarket pre Xmas offers)