Next step in the Sprint engine saga was to get the front cover off which didn't take too long. This is because I am getting used to it by now and also I used my new air impact wrench.
For those of you familiar with the Sprint engine you will probably recognise the duplex timing chain running down to the cranckshaft sprocket and back up to the jackshaft sprocket - what is not normal is the "half-moon" tab lock washer jammed in down there!
Having removed that carefully I went looking for the missing camshaft sprocket bolt - which should also be at the top of the engine. By lying headfirst into the engine bay upside down (!) whilst using the excellent combined torch and magnetic probe (also used as a radio mike!!) given to me by Paul Darbyshire I spotted the missing bolt and removed it.
If you look very carefully you can see it in the pic below sitting on the front level of the sump - definitely not where it's supposed to be!!