I was overweight flying NCE-LHR awhile ago. It was a BD flight with an AF codeshare, the counter was manned by subcontracted workers who also seemed to work the KLM flights. I have top status on all BD, KL, and DL (Skyteam). The woman was insistant that I would have to pay overweight. I whipped out the Skyteam card and she said I would still have to pay something. I whipped out the KLM card and she said I'd have to pay something smaller. I whipped out the BD and she said that although it covered my extra piece, I was still overweight (BTW here guys, Biz tkt, 2 pieces, 1 about 28 kilos, the other 32 or so).

Supervisor called over, was very impressed by cards, and asked me with a wink "when I was connecting to a flight to the US". Lucky for me that I had an open, i.e. way in the future half of a Biz ticket in my bag. Showed that, and all was well.

Nice always seems to be a problem with this issue.