I’ve had a look on line and looked through a few books both for the telescope and for the event (Lord Morison handing over the telescope) and I can’t find anything. As you say, several of similar design, but none VERY close. The altitude bar, the fixings to the mount, the location of the focus knobs, the combination of exposed and covered brass…
It would probably be worth contacting the antique Telescope Society. Also try the Society for the History of Astronomy as they will likely put a picture of it in a coming publication to broaden exposure.
James [Librarian for the Society for the History of Astronomy]