Just a thought here, but doesn't imposing a contract on workers without their consent or agreement constitute forced labour? If so it's a breach of article 4 of the Human Rights Act. "A person is subjected to forced labour when the person does not voluntarily consent to perform work but does so because of threats made, either physical or psychological."
It seems to fit the bill to me. After all Hunt in attempting to pave the way to a return to exploitative work practices, is trying to force us to perform work we haven't consented to. Not exactly slavery I know, but the thin end of the wedge?