Whilst in no way am I doubting the story as related to youself. Could the vase you mention be decanter minus the stopper. Below is a picture of Betty Reid (who dealt with the office side of Monart) with the full set of the Wedding Gift and as can be seen no vase in the set, also in all the literature I have read makes no mention of vase in the set, there was decanters, sweetmeat dishes, goblets, finger bowls and fruit bowl made for the gift.
The rest of the story sounds correct, in 1947 Moncrieff glass works was commissioned to make a gift for the royal couple, it was Paul Ysart and his apprentice Chic Young who made the set.
Image reproduced with the kind permission of Perth Museum.