Damage to neighbours car by shed roofing-felt

[PrincessBong]

In the recent high winds the felt from our shed roof blew off and lodged under our neighbour's car causing some damage. He is threatening to take us to court for the costs. He claims we have not maintained the shed properly - it is true the felt has come off before. However, my husband has carried out repairs and followed the advice from the supplier to use heavy-duty felt. Are we liaible? Our house insurance company says no but he is determined to recover the cost of repairs from us. Many thanks for any advice/views.