Thanks to Terry for the page and plate references from the Hajdamach book.
I had ooked at that earlier but missed an important point. In the text for the plate it states:
... Tall vase, Stuart Crystal
Given Charles Hajdamach's insistence on accuracy, as can be confimed by Frank for the editing of the Ysart Glass book, I trust the "Stuart & Sons" attribution for the vase as the piece was from the Stuart Crystal factory.
[But I also bear in mind the fact that a very good piece of Bohemian cut and decorated white and blue overlay glass was once believed to be by Richardson as it used to be in Benjamin Richardson's collection - Hajdamach, page 91, colour plate 8.]
I agree that since the book image of the Stuart & Sons vase is b&w it is difficult to assess the details, particularly of the coloured parts. However, under a loop it can be seen that the trails are formed as clear glass surrounding a coloured "eye". Whether that "eye" is green or blue - or both - cannot be determined. The clear glass continues as a well-moulded length to form the trail. This description fits the example I have shown.
Of the examples of this type of decoration that might be Bohemian, or those that were indeed confirmed in the Truiits' book as Harrach, they all seem to have full (or part) green in the stems of the trails, In fact most seem to have been formed in a tapering shape - akin to tadpoles.
It is the very fine, and non-tapering, form of the clear trails that I have linked to Stuart & Sons. So it would useful to know of other examples with that feature that can be identifed as other than Stuart.
My original message for my friend's vase has been updated with a note that an indistinct etched mark has now been found on the brim (I had mainly studied the base area as that was where I expected any mark to be!). When I next see the vase I will try to get images of the mark. Even if it is indistinct, it may show enough shape and form to identify it.