Thank you both for your replies. The vagueness of the BA form had me concerned that they were going to respond with something to the effect of 'here's the $30 for the rental car extension, but you didn't do anything to justify the rest of the €1200'.

I'm making no assumptions about Brexit other than that I don't know anything about what will happen in the coming weeks regarding Britain and it's relationship with the EU and its laws.

For what it's worth, as the pilot described it on last night's flight, it kind of seemed like BA couldn't organise a replacement pilot for the return trip to be sent from London with the incoming plane. I've put the claim in and will wait and see what happens.

Thanks again