Two experiences -- neither on BA, so apologies if these are out of scope

Some years ago I had a one day r/t on AC in the Canadian Maritimes. A-B in the earlyish morning (I cannot now recall exactly where A or B were), I was the sole passenger in J out of 16 possible seats. B-A in the evening, turned out to be the same aircraft, the same crew, again I was the sole J passenger, and I insisted on taking the same seat. It was agreed that I did not need an attendant standing in front of me to perform the safety demo.

More recently (3-4 weeks ago) I was the sole J passenger on KLM, CDG-AMS, again out of 16 seats. There were only about 20 pax in Y. This was the day before the Olympics started, and apparently the inbound (AMS-CDG) had been bursting at the seams.