Maybe the glass blower didn't put enough molten glass to fill the mould?
Emmi, you're implying, no, saying an experienced glass maker would not take a gather that was big enough to make a standard size vase. I don't really think the suggestion stands up to any stutiny.
To me, in the photos of this vase, the gap at the top is consistant with the gaps lower down, suggesting that the vase has been carefully cut down and given a polished rim that is totally consistant with the original finish. If I understand you (and recall) correctly there should be larger gap between the pattern and the rim, whereas here it seems to be the same as the rest of the vase. At one stage this work would have been worth doing as the value of the textured pieces was so high, however nowadays this is far more questionable commercially. (This is not to say I condone such 'restoration' - however, of course it could have been a much loved item that has been repaired, just as much as an unscrupulous 'repair' for gain.)
Which brings me to the question of collectability. As a cut down piece it has lost all its value as a collectable item.
IF on the other hand, it is in fact original, then of course it would have value as an unusual example.
£6.00 is a far price for such an item, but I seriously doubt that it is as made originally

Nigel