Well, I've done what Shifty wisely suggested. I've lifted the front end of the rocker cover just enough to take a peek underneath. First thing I reassuringly saw was a nice, shiny chain looped over the cam sprocket. But then I remembered what the main dealer service manager had told me: "You want to make sure the crankshaft sprocket hasn't fallen down the sump, as well, mate. It happens."
So I borrowed a neighbour to key the starter over whilst I observed and saw both chain and camshaft spinning merrily over just as they should. Result!
But now the electrical hunt begins....
why are you mucking about? just get it on the diagnostics