The flask is in a Michael Harris design, currently called "Crystal blue stripe" - a pattern which has been a mainstay of Mdina production almost from the very start and continued today.
I think, however, that this is a fairly recent shape. Earlier flasks had a more rounded than triangular bottom part. Don't quote me on that, I'm not positive and with Mdina you don't always know - shapes can be a bit haphazard! However, stoppers with this pattern in them are a fairly recent feature.
Is the inside neck of the flask ground to take a stopper?
The stopper you have is in a different pattern completely and probably belongs to another piece - in that same pattern. Given the very deep "jewell-like" blue of the stopper, it's a later-ish (well post Harris) one - but not neccessarily the same period as the flask.
However, if you find a stopperless something in that pattern, you might be able to put it in that to complete it.
John - I've got spare stopperless bottles in Ming, if you'd like one!
Am I making any sense? I think I'm confusing myself!
Most older stoppered pieces from Mdina are "marriages" - given how they were sold. It's quite ok.
Cross-posting confusio :pb: - it's perfectly possible the flask did have a stopper - but I'm also positive it would be in the stripe pattern. The two different patterns don't really work, do they?