Hi, everyone
after a long time I now have an unequivocal identification of the vase. I was at the National Museum Leerdam last week but couldn't find the vase. I then wrote to the curator of the museum, who answered promptly. The vase is from 1943 by Andries Copier and is also shown in a book about the glass school in Leerdam. I am very happy to now have a truly unequivocal expertise
Monika