I tried all sorts of permutations, lots of choke, no choke, a little choke, same with throttle, new plugs. Bought a small ultrasonic cleaner and stripped and reassembled the carb with a new gasket set. Still no improvement *sad2.
Checked the spark which didn’t appear to be consistent so I got the mag refurbished at Priory Magnetos. It took me a while to time it up again but got there in the end and it started

, once

. Couldn’t get it to start again that day so gave up.
I left it all this week until yesterday afternoon. Got home from work early so decided to try again. Turned the petrol on, tickled the carb until finger wet, no choke, no throttle and it started on tickover

. Let it warm up, stopped it then straightaway no throttle, no choke, started on tickover again. Thought I’d cracked it so left it 10 mins tried it again but wouldn’t start no matter what I tried. So I walked away and went down the pub.
That’s where I am at the moment folks. Going to try again this weekend, any advice would be very welcome.