BAE Systems and Rolls-Royce’s ability to deliver the new Successor nuclear missile submarines to replace the ageing Trident fleet faces fresh doubts ahead of a crucial vote on the huge project.

On Monday MPs will decide on whether to press ahead with the programme - the biggest UK defence deal for decades with a £30bn price tag and £10bn contingency fund to deal with snags - with major worries about their record for building submarines.

Both are involved with the current programme building Astute-class attack submarines, but this has been littered with problems.