It was a bare-bones demonstration of politics as theatre. Today, the Prime Minister went to Barrow-in-Furness on the Cumbrian coast to visit BAE Systems Submarines. The shipyard there has built all but three of the Royal Navy’s nuclear-powered submarines – the others were turned out by Cammell Laird of Birkenhead – and are undertaking the construction of the four Dreadnought-class ballistic missile submarines which will carry Britain’s nuclear deterrent through the 2030s and beyond.

The theatricality came from the fact that Andy Burnham went to Barrow to make an announcement which was inevitable and predictable. Its details were released to the media by Downing Street in advance of the Prime Minister’s appearance: essentially a trip to a submarine yard to tell an audience via television or internet something which had to happen and the details of which were already publicly available.

The Dreadnought-class boats are still many years away from entering service. Steel has been cut on all four – HMS Dreadnought, HMS Valiant, HMS Warspite and HMS King George VI – but only the lead vessel has been laid down and she is not expected to be commissioned until the early 2030s.

The programme could not be changed in any meaningful way short of cancellation