Sorry I didn't pop in earlier - I thought the title was going to be about a paperweight, (which I suppose it is-ish!).
Anyway, yes, I'd say it was Mdina. Lesley Jackson says that Isle of Wight Studio Glass did these, trailing molten glass on the marver in 1976, and I have seen a few. However they were definitely done at Mdina because I have a huge one, signed by Michael Harris. I also have a few of these little bookend-y ones, marked Mdina.