And the tories'd have carte blanche to tear up worker's rights legislation that originated from our EU membership....
That's actually a falsehood. The reality is any rights in this country are being eroded by EU legislation as they impose a one size fits all across the board. The determination of zero hours contracts comes from the EU from where most industrial backstepping originates.
the legislation on contractual obligations comes from the EU. All EU legislation is done in double speak that is open to determination by national governments, all open ended to allow change without negotiation.
the minimum wage, much heralded allowed corporates to be 'legally compliant' without having to pay fair or living wages, that is being furthered by driving real wage terms downwards
edit, but this does play into the hands of those with a more vested corporate interest, such as the tories and new labour