I've already heard Labour being blamed for this tory **** up!
tbh IMO there's some truth in this.
Among the many groups who voted Leave were a large number of "traditional Labour voters" - working class people who really haven't seen any improvement in their circumstances and who have been hit really, really hard by the government's austerity programme. They've been repeatedly told that it's all the EU's fault and in particular it's the influx of EU migrants who are driving down wages and causing strain on local services.
The Labour Party could have, should have, put out a strong, positive, pro-EU message highlighting everything that the EU does for "hard working Britains". Instead, because the leader was a reluctant Remain supporter (albeit his reasons for being anti-EU were diametrically opposed to most Leave supporters) and because of the overwhelmingly negative messaging of the Remain campaign, there wasn't a clear, positive message from the party.
Indeed Jeremy Corbyn's measured style and calm demeanour means that he comes across as lukewarm even when talking about subjects about which he is passionate.