Well, my bad luck is sticking around. After the first session at Brands Hatch I noticed some blue dust on the inner wing, traced it back towards the engine. Took the cambelt cover off and the belt had a big deep groove around it as if something was rubbing on it. So took the front off the engine and found a chunk of metal wedged between the cambelt and the oil pump. Then noticed the cambelt tensioner bearing/pulley had grease hanging out of it. Basically that piece of metal was the dust cover from the bearing. How random is that one. Luckily Sumo Power had a spare cambelt and bearing so got it running again but I was so close to another head full of bent valves! Got it running for the qualifying and final but was on the back foot a bit missing a session and bedding in new brake pads.