Have to disagree Gary, regarding "it was almost impossible to get a complete match in all the dimensions for any certain shape,"
The Ysart family were all capable to make pieces to precise dimensions. While this might be true for some modern glass artists, glass blowers with a traditional training would be able to deliver to very close tolerances., That they chose not to with Monart is a completely different perspective. The rare matched Monart pairs are where you do find exact matches as too with lamp base necks and shades.
In light of what Frank and Sue have said, I will rephrase my original statement.
The Ysart's were able to make pieces to precise dimensions. But for what every reason, they did not keep to the same dimensions in every production run.
Hence the difference in Roberta's three A shape vases.
Below is two A shape vases. The one on the left has a Monart Ware label (V11:A:56), the dimensions are, height 17.5cm, width of opening 8.5cm and round the widest point 51cm.
The one on the right is a pre war piece, the dimensions are, height 16.5, width of opening 10cm and round the widest point 52.5cm.
Gary