Help 1996 M600 non starter

So the strangest thing.
I have spent the last couple of years getting my bike back on the road after being mothballed for almost sixteen years. All threw this time I have fired it up with no issues.
Cut to the day of the MOT, wheeled it out onto the street, would not start and has not since (7 days ish)
Turns over ok went threw all the idiots list tracked down dodgy coil, swapped that out but still no joy.Checked the fuel and it seems to be getting some but unsure of the flow rate of these old vacuum style pumps and I'll get the odd backfire but that's it.
I am at a loss
Could be timing?

Help