Just updating, So as per Dave's picture my bolt turned out to be the same. So do not go by the Caterham parts page. Bolt type must relate to year not if fixed or V cam. The Caterham part number though is also the Ford number so nipping up the road I got the bolt for £6 Torque setting. Ignore the 115nm that is listed in many places. 40nm +90deg is much tighter and gets to a point where the bolt feels locked. I locked the flywheel, my air rattle gun would not fit between the bolt and chassis rail so had to use a torque wrench anyway. While at it, I cut a slot in the lower cam cover and shaved a bit of the lip off. I will now be able to do future work without the extra job of removing the crank bolt. The cover will come off with the lower retaining bolt removed, cover turned clockwise and pulled. Thanks Rob