The Labour party has always had a euro-skeptic minority.
It's interesting that whilst one of the reasons why Brexiters want to leave the EU is that EU protection of workers is too onerous and places us at a competitive disadvantage (presumably to our "natural" competition, the recently industrialised nations of the developing world

), Jeremy Corbyn's historic and well publicised opposition to the EU was due to the fact that he felt that the EU was too corporatist and did not provide sufficient protection for workers. I can understand why Jeremy Corbyn has revised his position, a post-Brexit UK would be far worse for workers than a UK in the EU.
Labour Party policy has however been pro-Europe and so the Labour Party officially adopting a "remain" position is hardly surprising and doesn't represent a change of position for the party as a whole.
As the Labour party leader and prospective future Prime Minister, Corbyn should be promising increased protection for workers as part of the Labour manifesto, if he believes in it and thinks it's a vote winner.
It's pretty pathetic for a party that aspires to be in power to have to rely on Mommy EU to implement their policies for them.
And I wouldn't expect the vast majority of Tory voters to favour reduced worker protection either. So if the Tories do introduce such reduced worker rights they harm their own chances of retaining power in future elections.
Two sides of the coin above. To be honest, I've been resigned to Brexit mentally for sometime mostly as I have a complete lack of faith in the British people to make the right decision.
I don't particularly fear Brexit as a thing, in my situation I doubt it will make a huge difference either way. I don't think I would be immediately effected beyond mild inconvenience or at least no worse than I would be by some Westminster decisions I don't agree with either.
What I do fear is what a new reinvigorated right would do with the powers they have won back. And Corbyn too is right to fear that because even he probably knows he's not going to win the next election against Bojo. Don't for a second rely on Tories not to do what they want to do because the past few years repeatedly prove to them that turkeys will vote for Tory Christmas as long as its sold to them the right way. They can just lie and then do it anyway once they are elected and it will all be forgotten come the next election.
One thing I do agree with Brexiters on sadly is when they talk about British values being eroded by the EU. Its true that the EU and British values are not aligned. Because the truth is the core British values that we see on display across the country (and especially in the heart of Little England) are insular, xenophobic, racist, reactionary and obnoxious. Every social gain made has been made by dragging these people kicking and screaming against their will to at least pretend to adopt progressive values but the real truth is they never did. They long for a mythical English past of cricket on the village green, tea and cucumber sandwiches, calling their dog ****** and giving their kids golliwogs to play with then home to watch Jim Davidson on TV and repeats of Alf Garnett.
They think its an affront to British values to see a Polish shop, an Indian takeaway or god forbid a mosque in their towns. They wallow in their own sense of superiority and don't see the irony in invading Spanish beach resorts with their Union Jacks waving, singing songs about German bombers and deriding the local food, culture and way of life before sexually assaulting someone and throwing up on the beach for good measure.
Worse still are the small band of immigrants and their children who have bought into this 'British culture' and now seek to pull up the ladders behind them on their fellow man. Who would rather see other families condemned to poverty, separated, or just face down in the Med than let them share in the benefits that they demand they are entitled to but must be denied to everyone else.
These people decry the rest of the world as lazy scroungers, on the eye to take take take whatever they can get from the hard working English. These foreigners hate us and want to bring us down to their level, you see? We can't afford to help them. The country's full they insist. Why should my quality of life suffer they moan as they settle down to watch SKY TV on their 50" plasma with another case of cheap beer from Tescos only for their accountant to interrupt them with another 'can't lose' tax avoidance scam.
I voted Yes in 2014 to get away from them and the least I can do in 2016 is vote Remain to keep a lid on them. Post Brexit UK in 2019 with PM Boris hardly bears thinking about. Immigration will be the least of their worries. I doubt
anyone will want to move here. The bigger question might be how many will want to stick around?