You can't prove it was there and they can't prove it was you end of story. A tiler nearly cut my thumb of last year and turns out he wasn't insured. All he had to do was say that I done it my self, even though my wife and kids were standing three meters away as witnesses there was nothing a lawyer would do about it. Six weeks off work with a badly fractured thumb, the nail removed and nail bed stitched up and I couldn't claim him!! So I doubt very much this chancer can claim you.