I've had an email from Colin Moulding/XTC:
Paul
It sounds like a worthy cause, and the money is not an issue , but I can't really say right now whether I’ll be available.
I prefer to react to stuff when it comes through, so making a date , 4 months hence, would not be right for me.
Sorry for the lack of committal
Best
Colin
While it's a great pity he's declined at this point, I've thanked him for taking the time to come back to me.