I have been following this thread with interest as I have similar requirements to Thorpie for a steel hardtail.
So I have just called both Woodrup's and Bob Jackson's in Leeds about an 853 framed mountain bike, both were in the region of £550 to £600, but with Jackson's they were mentioning a 5 - 6 month waiting list!
It seems to compare quite nicely with the off the shelf bikes, as well as being relatively local and is significantly cheaper than Curtis. (Although the Curtis does look quite good!)