The only mark we could find was the missing tooth on the reluctor wheel on the flywheel. Using that as the mark gave us valve/piston contact when we tried turning the engine by hand.
I re-set the valve timing and (chain removed) slowly tuned the c/shaft until the piston met a valve. After marking the c/shaft and the c/case I turned the crank the other way until it stopped and marked the new position on the case. I then put a new mark exactly an the middle of the first two. This should be TDC. The mark on the c/shaft should then be, in theory, tdc on cyls 2/3 (or possibly 1/4). I put another mark on the shaft exactly opposite the first and then put another mark 2.5 teeth BTDC (18 teeth on pulley. 1 tooth = 20 deg. 2.5 teeth = 50 deg). I re-fitted the chain and turned over the engine by hand - so far so good.
The engine now starts but but sounds like it's missing on one cylinder. It doesn't list a new fault code so I'm guessing the cam phasing must be about right.
It looks like the engine might have hit a valve when it developed the fault.
The strange thing is, I still can't see any obvious marks on the flywheel unless the 'hole is a slightly deeper gap between the teeth.
If anyone can spot a flaw in my logic I would be interested to hear your comments. I have been known to be wrong before!