On my return home today I had caught up with an absolute crawler with a very low power motorcyle behind him, i had to follow the pair for a few miles and junctions. knowing the road I was ready to overtake on a stretch that has clear. It was clear I checked my mirrors and the motorcycle to see if he would overtake. After a short delay checking I indicated and accelerated to pass. As I am along side him he suddenly starts to swerve towards me making some small contact and scratching 2 panels. Thankfully he didn't come to any harm and there was no visible damage to the bike, we both stopped once safe to do so and exchanged details.

Will the insurance company likely see this as his fault, my fault or both? and subsequently clobber my premiums?