If my neighbour’s trampoline was to blow out of his garden and into mine, or on to my car parked in the street, would I be entitled to claim for any damage it caused?
Almost certainly: it would be a foreseeable accident, and your neighbour should have taken steps to anchor the structure to his lawn or turn it upside down to prevent it taking off. If you are aware that the trampoline is preparing for lift-off you should warn your neighbour, since it’s likely to be easier to prevent the damage than to actually get your neighbour to pay for repairs. He would probably be able to make a claim on his buildings insurance however.