Beijing - BA now using BGS lounges rather than CA's. No invitation needed, lounge has list of eligible BA pax. List includes status and cabin booked.
BGS lounges are an improvement on CA's lounges IMHO.
I was quite disappointed by the F Lounge. Much smaller and more crowded than the air china one (only 2 free seats last time I was there), with a smaller selection of foods. Quite dirty - for example the juices were in cracked and mucky jugs.
Of course Chinese lounges are never up to much so ones expectations are trimmed already!