In 1975, the Labour Party was famously split over the question of remaining in the EEC. While the party took no official position, those on the left of the party such as Michael Foot and Tony Benn wanted out. At the time, Jeremy Corbyn was still a young activist, and he voted to leave as well.
In 2016, the party, led by Corbyn and heavily influenced by the left after the demise of New Labour, took the position to Remain in the EU. While it has been said that Corbyn was a reluctant Remainer, why was there such a marked shift in the position of the left wing of the Party?