YouGov’s daily constituency-by-constituency estimate has this
A bare and not very workable majority requires 323. The last Survation poll had it even closer at only Labour only 1% behind which would narrow the gap further. Either way, those perennial coalitioners the Lib Dems would be too few to matter so the SNP would hold the balance.
While the ‘poll of polls’ for the last week has the Tories clear this does not take account of their catastrophic decline, even amongst the elderly, in the last few days, nor the Jezza surge.
So, the Tories try to run a minority government and get voted down on their first vote of no confidence. They daren’t call another election knowing that would further alienate the electorate, give Labour more time and maybe produce a clear overall Labour majority. The second party, Labour, have a go and the SNP back their progressive policies. As we proceed, the SNP leadership talk to the Labour leadership and negotiations get underway to ensure a soft Brexit and to further devolve powers to Scotland. Jeremy is not against this and Kezia will be either gone or told to STFU!
The above prediction of only 46 for the SNP is pessimistic to my mind but it doesn’t really matter that much if they hold the balance confidently and clearly.