Hopefully I can remember the timelines ...

Was due to fly BSL-LHR on 6th November. 10 days before the flight, BA cancelled it. I got my FTV back. I should have got cash I suppose, but they argued they hadn't actually gotten around to ticketing it so just returned the FTV. I didn't push the point as it was only for around £60.

But, as the cancellation was short and I was annoyed at their rolling cancellations, I completed BA's online form asking for E261 comp. Was refused.

First response: Cancelled due to operational reasons. I said that's unlikely as they cancelled two weeks' worth of flights.
Second response: We gave you enough notice. I replied stating that 10 days is less than 14 days.
Third response: Operational reasons. I replied asking if it was their final answer (no phone a friend).
Fourth response: Operational reasons. I replied asking again if it was their final answer.
Fifth response: Go away. Go to CEDR if you must.

I logged a CEDR. I stated that between the time BA sold the flight (mid Oct) and them cancelling it (end Oct), no rules had changed between Switzerland and the UK and Covid was a known entity and airlines had already sorted out their timetables to deal with it. Plus, Easyjet and Swiss were still flying between the two countries.

20.11.2020: Case logged with CEDR.
23.11.2020: Case accepted
??: BA asked for a delay
23.02.2021: BA submitted loads of documents proving that I had booked the flight (why?) and said flight was cancelled due to Covid
17.03.2021: CEDR appointed an adjudicator
10.04.2021: CEDR award me €250 (£217).

Reading the conclusion, CEDR stated that the flight was cancelled due to reasons of financial viability not due to any flight restrictions or issues regarding safely operating the flight with the crew.