Not trying to stir up this thread anymore than necessary, but a few years ago on a Dublin to London City flight, I happily received a gate upgrade to Club Europe. The previous flight had been cancelled, so the flight was heaving. While sitting in my seat, I noticed the FA counting passengers and looking perplexed. He finally approached a passenger sitting in the aisle seat across from me, and asked to see his boarding pass. The passenger was not ticketed for the cabin and was supposed to be many rows back. The passenger whined that the flight was very full and this appeared to be an empty seat, so he grabbed it. The FA patiently explained that it was for Club passengers only. Grumpy passenger continued to argue and said that he was an AA Platinum, a CEO of a company, etc. etc.
At this point, the FA told the passenger he could keep his seat, but he would not be provided with any food or refreshments.
Later in the flight, while I was munching my salad and sipping my champagne, I noticed the grumpy CEO giving me a death look, as everyone seemed to be partaking of the liquid hospitality with much enthusiasm. As promised by the FA, he was not given any food or drink.