Studio cup, CAB, CEB, LEB, EAB Mark?

Studio cup, EAB, CAB, CEB, LEB ? Mark
Upright form.
Mark looks familiar but can’t find it in book.
60s 70s shape.

A couple more examples here. Charlie Boyce of Aysgarth Pottery says it's not his. David Brown has been suggested, but that's unlikely. One turned up (below) with AB written on the base which is similar to Alan Beastow's mark so may be an unrecorded mark for him but his mark is usually with a dot (AB.) on stoneware. At the moment it's still a mystery