Exporting Misery
We quite rightly have laws in the UK which protect workers against exploitation, by restricting maximum working time, obliging employers to provide toilet and refreshment facilities and breaks for the use thereof, outlawing child labour, paying a minimum wage, guaranteeing the right to belong to a trade union and so forth.
Allowing the import of goods manufactured under conditions which would not be acceptable here subverts all this. It's saying, there are ways in which it's not OK to treat a British worker -- but it's fine to treat a Chinese worker in those same ways. How is this not racism?
Until we place a total ban on the import of any goods produced under conditions which would not be acceptable in the destination country, we are exporting misery. (And not doing our own workers any favours, if they are unemployed because everyone is buying cheap quasi-legal imports.)