OK so yesterday I eventually got round to replacing the steering shaft UJ. Bit of a pig to do on a right hand drive V8. I carefully marked the top and bottom positions to ensure that it would be in line when I did the swap.
On mine though the lower clamp part can only go one way as thare is a plastic guide lug on the rack. That meant that the upper clamp was not in the same orientation as before so now the steering wheel is off. Tomorrow when it's light I'll whip it off and straighten it up. If it's between splines then I will have to adjust the track arms a bit.
Update on outcome later.