Hi, I would say definitely NOT Ditchfield as their pieces since 1982 always have 1 of 3 things engraved on base:
1) Just GLASFORM (made by a co-worker and NOTdesigned by John)
2) GLASFORM and J.Ditchfield in script (made by a co-worker but designed by John Ditchfield)
3) GLASFORM, J.Ditchfield in script and unique reference number (designed and made by John Ditchfield)