Now resolved -

So fuel wasn't the issue, I wasn't sure I was getting a spark or if the crank sensor / timing was an issue, so a quick spray of brake cleaner down the throttle body and the engine fired up!

I think what caused the issue was my flat battery after being stood a few weeks, even after a charge it was a tired old battery in need of replacement. The fresh battery helped but it still only cranked, no start but what I noticed it was cranking faster than it should, almost like no compression or timing chain snapped!

I guess my constant cranking and fuelling flooded and washed out the bores of oil, lost compression? The brake cleaner just helped get that initial combustion, burn off any residual fuel and get the oil pressure up enough to restore compression in the bores?

All fine now and running / starting perfectly as before!

Cheers for all your input and advice.