laverdabru - I saw that one, which to me looked a bit rough, at an expensive £125 with a serial/batch number 623. The one I was thinking of buying is £160 but looks to be in exceptionally nice condition from a private seller called Stephen in Sutton Coldfield.
I emailed him to check it had a rifled barrel and also asked for the serial/batch number which he told me was 653. I also asked if he was a member of BBS or AGF -- he isn't which, I have to admit, makes me cautious.

Binners - I know Peter, I know, but Kempton is just too far to travel these days otherwise I would be there (especially if the above Junior was for sale) even though my wallet would probably take a battering!