Noone that I know of who were travelling to Israel from London. I know someone frum who works at BA and he told me that BA is aware of peak demand for pre-Pesach travel, and he was quite sure they would do everything possible to keep flights to Tel Aviv. Looks like they were cancelling long-haul flights where they can consolidate passengers from multiple flights into a fewer flights (like having 3 JFK-LHR flights instead of 5).
The most vulnerable routes are domestic and short-haul out of LHR. I've flown earlier this week to Amsterdam without problem, though my trip to Germany tomorrow would be affected on the way out so I switched to Lufthansa. Nesia tova.