I don't know details about UK, but Polish labor laws are quite strong (in terms of protecting the workers), which is no suprise, given that they were created in 1974, i.e. under the Communist regime (similar for public housing, education, tenant protection etc. BTW - all written by communists and not changed much since). I wouldn't be surprised if they were stronger than in Denmark or Sweden, where the policies (from what I've read) focus on helping the unemployed/laid off, but don't meddle into the employee-employer relationship as much.
Poland had a much stronger local union structure, along socialist lines outside party control, which is why Solidarity union activism was possible. My knowledge of that time in Poland is pretty limited though.
Any facts to back this claim? I'd say the US Democratic party is more left wing than Europe's major parties now.