Could be TW/ Wirkkala ?. I have quite a number of oval section vases which seem to have been made by everyone. I have them by Gullaskruf, Johansfors, Sea Glasbruk, Leerdam, VSL and Iittala - and a few unidentified ones which may or may not be engraved on Kosta blanks. The numbers on these go all over the place - I've given up trying to ID them.