This - one non specific snippet of info - is standard practice from BA, though it's not very helpful without the details. In hindsight, which is a wonderful concept, you best ring BA at BDA, or speak to them the next day, to find out what their version of events is. The ground staff at BDA are a chatty bunch so I'm surprised they didn't tell you anyway, or the captain on board in his/her preamble. If this was bird strike, for example, or lightning strike, then this wouldn't be a reason to deny compensation. If it was damage by a truck working for BA, again it is not grounds for compensation. If it was caused by another aircraft ramming into the BA jet, that would be another matter altogether. So the details matter, and that's what we lack here. I was hoping for some information on thebasource.com but I can't spot anything.

The good news is that the Regulations make it the job of the airline to justify extraordinary circumstances, not your job to disprove it. The bad news is that you may have to spend some effort to get to that point.

At this stage, I would ask BA to tell you precisely what the damage was, where it happened and on what date. Without being heavy handed about it, you could indicate that the rapid provision of this information will allow you to decide whether to take the matter further. Armed with that information we can either say "don't bother" or "keep on at it". You could of course think about an immediate recourse to MCOL, in order the force the information out, but I hope you can avoid that.