A row over defence spending has erupted after a respected think tank said the Government was breaking its promise on spending two per cent of GDP on the military budget.

The International Institute for Strategic Studies (IISS) said Britain’s defence spending had dipped below the Nato benchmark figure, despite the government vowing to meet the target.

The analysis comes only days after Theresa May had boasted to Donald Trump of Britain’s military spending and lectured Britain’s European allies to spend more.