Dave: Of course we will not be able to tell until there have been a few local elections and the real test will be the next GE. I cannot see any minority party, however popular, getting enough support to form a government in 4 years time.

Of course, the Welsh Senedd elections next year could provide an earlier test. Labour have led the Senedd since its inception in 1999.
If that ceases to be the case it will be a major upset, and could be a guide to what will happen in UK a few years later.