Exactly right, it was key Labour seats that put the Leave vote over the top. A bloke like Corbyn is probably the only one who could unite the competing interests within the party.Corbyn's heart clearly wasnt in remain. He put some token effort in but it was pretty clear he couldnt give a toss.
The Blairites will try to use this to mount a challenge, but Labour would be better off rallying behind Corbyn and putting up a united front as the Tories will be trying to rip themselves apart after this.