Thank you both for your replies. My immediate thought was Webb or Whitefriars so I examined the base very closely but cannot find he usual etched Webb mark. I also listed it on the Is it Whitefriars site where there has been no written response but it has received 2 "no" votes.
I looked at the link to the auction you mentioned Ann and the shape is identical. My example is in lilac or pale purple coloured glass whereas with the auctioned one, the purple colouring looked uneven. However, they are surely linked in some way due to the exactness of the shape.
I think I need to enlist a pair of younger eyes to examine the base - I have been caught out before with these faint etched marks - though my gut eaction was that it was Whitefriars.
Regards
John