Here's an update:
Stripped the panels off and before I had even removed them I could see the problem. The main fuel line was loose and hanging very close to the end of the tank inlet.
Sorry about the quality of the photo, I was focused on checking out that connection.
So the connector on the pipe as well as the part that sits behind the ridge on the tank inlet are fine, there are no signs of cracks or breaks. Problem is that once connected back up properly I can take hold of the pipe and, without much force at all, full the pipe off again, the clip part just pops out of it's socket and away it comes.
With the pipe connected the bike primes and starts without any problems, there is no low idle and all is well.
The question then is this. If it takes very little pressure to remove this clip, what's to stop it just working its way off again. Are they supposed to have a little give in them as some kind of safety feature (in case the vent pipe get's blocked and to stop the tank going bang?
What is the consensus here please. I could add something to stop the clip coming loose, careful use of a cable tie would probably suffice, but would that then make it dangerous?
The bike is in bits for now so any speedy replies (before the light goes) would be greatly appreciated.