Whatever caused it, it was bad: dizzy spells, wobbly knees, and sitting on the loo for hours (and when I wasn't sitting on it, I had my head in it).
Then I spent a whole day in bed to get over it quickly as we had a dinner date at the club the following evening with neighbours to celebrate our anniversary of something-or-other (don't tell my wife I forgot! suffice it to say that the date coincides with Bastille Day which started the French Revolution; that should be hint enough!}
I got through dinner all right having taken the precaution of ordering a bucket of champagne. I don't like champagne; I wanted the bucket just in case!