GMB Scotland warned David Cameron yesterday that the Royal Navy’s new flagship supercarriers can “rust at Rosyth” if any compulsory redundancies are made over the delayed contract for new naval frigates.

The union has mooted the idea that shipyard workers could hold the two supercarriers hostage in port to halt any forced job losses at the BAE yard on the Clyde.

GMB Scotland officer Gary Cook said that the joint unions at Rosyth, Govan and Scotstoun were prepared to do “whatever it takes” to defend jobs.