Anne, there is a vase shown in the Markhbeinn catalogue (mainly Inwald's glass) of 1936, that resembles your piece. The difference appears to be that on the illustration (drawing) in the catalogue, there are not as many V shapes - but the height (27cm), pattern and top/base shaping all appear to match.
I admit I did think "Inwald" when I looked at your photos - it's clearly a quality piece, and the ground base looks right.