@MasterGland
Many people on the left voted leave because that was the true Socialist position. The EU is a neo liberal economic project , hence why JC has always been anti EU. Many socialists saw that they were voting against an institution that forbid state support of industry etc. (unless they were banks...). There was also a strong remain camp on the right, led by Ken Clarke, that believed we were too entwined with the EU to leave. A Burkean perspective. There was also some genuine racists, on the right and left, who misunderstood what a vote for leave meant. Assuming it would lead to less immigration. These are complex issues and it is frustrating to see the broad brush strokes that get bandied about.
Yes, I am not sure where it has happened, but there is a big misunderstanding by many people around what constitutes the left. That's not a criticism, it is now so widespread many people have only heard it from that perspective. But it prevents them understanding the situation.
For example this:
For years and years people have been ignored they were not listened to and here we are. Why the liberal left has become so detached from so many working class people (in other parts of Europe and in the states) is baffling at times
Liberals and the left are NOT the same. Liberals typically believe, economically, in little regulation, free trade, and movement of capital and movement of labour. They don't usually like protectionism, unions, or national support of certain industries. Socially they believe in individualism. These tend to be middle class values to a large extent, and also the values of capitalism.
Leftism is very different. Traditional conservatism is very different. In significant ways they are more like each other than they are like liberalism, which is why you sometimes see the working classes and the elites sympathetic to each other more than either are to the middle classes (it really isn't forelock tugging as some people, who apparently really don't believe in classism, like to call it.)
The LP used to be leftist but are now mostly liberal, and the Tories used to be conservative and are now mostly liberal. (So no need for the Liberal party, really.)
So the answer is, that the LP is out of touch with the working classes because they are no longer a working class party. They area liberal, middle class party, and their policies are those which are appealing to the values and needs of the middle classes.