I would tend quite strongly towards Mtarfa.
Mtarfa was set up by Paul Said in 1981, and developed designs from those he was doing at Mdina - this fits in with this sort of thing being produced at Mdina, at this time, but also would explain the differences - the much wider flared rim, the more angular shapes of the coloured bits, the cloudier appearance of the white in the background, and the squater base shape - with the slightly shorter almost double bulbous base rather than simply a rounded one.
Have to say, I haven't paid much attention to this particular style of post-Harris work at Mdina - I'm not at all fond of it. I don't like white in glass and I don't like splodgy too much, unless it's bright and garish.