They can both be true. Fog disrupted a lot of flights, and BA changed aircraft allocations to try to minimise delays across their whole network which caused your flight to be delayed 4 hours.
Hopefully you had a safe flight. Unfortunately I don't think you'll get compensated for it. Not sure why the captains name is needed, the flight number and date would be enough.
Thanks for the concern. We eventually landed at our destination, so no worries there. But I have some really good "evidence" that points in my favor, so weŽll see how it turns out.
The most irritating thing is the "lame" response from Customer Service and also the turnover time, but I guess they get quite a few requests/claims