While the given figures are as good as any, take all with a pinch / dollop of salt, an accountant type can come up with any figure they like, good or bad, to suit agendas...
As for the Top Gear programmes, I would guess they were regarded as recruiting aids, possibly rightly.
The fact J.Clarkson is a staunch supporter of ' Help For Heroes ' can't do any harm either, and there's always the argument ( ? ) that it was unusual training for the Typhoon pilot ( the Sea Harrier drag race seems a pretty standard manouvre ), and the aircraft if not there would have been in use anyway.
So, either do it for free for the publicity, ( the BBC may have contributed, don't know ), or make up a figure like telephone numbers...