In spite of the right-wing press attacking him relentlessly, despite people like Mandleson working to undermine him "every single day" and his ilk driving a 'coup' against him, Corbyn faced them all down, campaigned brilliantly and took 40% of the vote. It seems increased youth turnout was real -- they took Canterbury ffs! Corbyn drove that. Anecdotally, I know people who weren't political and who never voted in a general election before voting for Corbyn's Labour, very specifically because of Corbyn.
The fact is, The Tories have under-estimated Corbyn, the same as the Blairites have continually. Look at how May folded under a bit of scrutiny -- how do you think she'd have coped with the sort of onslaught that Corbyn faced? He is a tough operator and has stayed a very decent man throughout.
It wasn't only the sh1te Tory manifesto that turned the tide -- Labour's manifesto was very popular and well thought out (I expect the usual arrogant bluster in response to that) and many people voted for Corbyn hoping for those policies.
Who here plumped for 'Hung Parliament' in the little GG poll then?