The left wing was traditionally the party of the working classes. The poor. The less educated.
They were worst hit by the flood of cheap EU labour. They were undercut by people who were "doing their year" in the UK to gain language skills so would accept minimum wage jobs even though they were relatively well skilled.
They were undercut by people who owned their own homes in Poland or Czech Republic so were not trying to rent or buy family homes in the UK. By people who could house-share and send money back "home" where it bought a lot more than it did here.
They were told by middle classes that the Eastern European workers were better than they were, worked harder, were more polite - all the time.
They were in competition for jobs and homes and school places with millions of people - not just locals. And anyone could do it because the in-work benefits made it possible.
The rich middle classes didn't have to worry that 80% of the school places would be taken by people suddenly buying in a wealthy suburb.
Working conditions are worse than they have been in long time. The zero hours contracts on which people get a text at 6am to tell them how much work they'll get - and if they are "difficult" someone else will do it - that is brutal. It rarely hits social workers, bankers, teachers, lawyers - it hits removals men and warehouse pickers, construction workers and carers, retail staff and bin men .
Brexit may affect house prices and pensions and jobs in universities - but that makes no difference to the working poor.
As for racism, the UK is one of the least racist countries in the EU and non-white British found racism worse from non-British Europeans than from locals who had grown up in mixed areas. Locals were often excluded from conversations and work related banter because it all took place in another language.
The poor, low-skilled, working classes found they were working with teams of people who did not share a language or a culture or a local connection - and told that they were racist to feel uncomfortable.
So there were sound left-wing reasons for voting out. If you really believe the left is the party of the poor and the workers that is.