What a wonderful break through Sam!! I wonder if the fact that the Guildhall Library is currently closed will mean that the librarians cannot work or if the library is just closed to visitors?
I suspect that the City of London fringe would have been purchased from a jeweller or dealer in antiques and, if it had previously belonged to the Ranee, it would not have been purchased directly from her.
I have never found any press items on the provenance of the tiara, where the City purchased it or the price. That is in marked contrast to the gifts given to Queen Alexandra and Queen Mary, but in line with the policy adopted for the wedding of Princess Mary and QEQM.
The City of London fringe cannot have been the Vladimir fringe as it was seen worn long after Princess Marina married.
Another interesting piece of information has just come up in the webinar of the Cartiers and the British Royals where at 1.16.17 it says that Princess Marina wore her mother's tiara on her wedding day.
For the webinar see
If Geoffery Munn is correct and the City of London fringe does not convert to a necklace it seems to my untrained eye that it would not have been able to have been worn as a bandeau as we saw the Ranee wear her fringe tiara. I think that for a tiara to be worn like that, there would need to be a degree of flexibility. Nor do I think that the Ranee's tiara flares at the side. But perhaps I am mistaken. Fringes, like collet necklaces are something which I have no real eye for!