Thanks Zilog and once again Ben.
It is a production frame Ben.
I have tried to act responsibly in getting this sorted out in a civilised manner and have spoken to the manufacture in question in a respectful way via initially a phone call and subsequently emails.
Perhaps with this latest information I should talk to them again.
They no longer produce the frame in question for what ever reason so I begrudgingly accepted their offer of a half price frame lower down in their range so I don't know how that would affect my claim.
This was before I was given the evaluation of the damage by the independent frame maker mentioned.
I did try to give them the opportunity to look at the frame as it was only out of warranty by 4 months and it really hasn't been used. I dawned on me after accepting their offer the 2nd hand shimano hollow tech bb and cassette fitted outlived the frame as mentioned on another thread!!
I suppose I was rather disappointed as when I spotted the crack I really wasn't worried. I thought its shame for a nice frame to go but they're good guys so this isn't going to be a problem. I took photos of the seat post insertion, striped it there and then and boxed it up ready to send back for them to inspect at their request. Despite offering to pay the carriage to get it to them for their opinion they weren't interested in seeing the frame. They also weren't sounding too surprised it cracked either!