It looks similar to Grimwade 3905 (William Tant, probably), but looking closely it appears to have those little nicks on the base of the 'W' that we discused in this post:
Having found Trev had replied to you three minutes earlier than me with the same conclusion but with another candidate for the mark a review is required.
It seems to me the outline of the punch here is different from the one previously discussed and more like that of Grimwade 3905 although I agree there are nicks at the base of both letters W.