My cancelled flight was SFO - LHR on 15.04. When I first called BA I was told I could not be rebooked as they had closed down the system for all new bookings and rebookings. I told them I would try again the next day. I did call next day - Friday 16.04. - and asked if I could be rebooked onto a flight from BOS to LHR on Friday 23. They said yes, there was a seat, so I took that. I then made my own way from where I was, to BOS.

When I was in BOS I met a guy in the hotel who had been on standby 3 times on Wed 21 and Thu 22nd, all times he had to come back to the hotel as they flights he wanted to get on were not operating. I don't have the full story on that but deduced that the first flight operating was either on Thu or Fri 23, from BOS at least.

I could of course have been re-routed from other places in the US, at an earlier date, but opted not to do this as there was such a high chance those flights would not be operating. In the end it looks like I made a wise decision.