Chalkstorm is a route which climbs a short slab (~4 metres) to a break where gear can be placed then follows another slab to the top (~10 metres, to give a 14 metre route). The crux move is stepping off good footholds just above the break. I (Tom) completed this move and was moving steadily up the slab. I gained some crimps with my hands at around 8-10 metres off the floor and it being a hot day my fingers slipped off them. I felt myself pulling away from the rock and almost recovered it by really bearing down with my right hand on the crimp but it didn't work and I fell, turning away from the rock as I did so. I was too far above the gear for it to be of any use so hit the deck. This led to a swollen left ankle, which was treated at the Northern General hospital the day after with a moon boot to wear for 4 weeks, and diagnosed as a bad sprain with a very minor chip fracture off the back of the heel. Skidding down the slab also ripped holes in my trousers seat!