The general in charge of the country’s £16bn-a-year defence equipment and support budget has ordered an unprecedented crackdown on spending in a sign of the cash crisis at the Ministry of Defence.

In an internal memo sent to MoD officials earlier this month, a copy of which has been obtained by the Financial Times, General Sir Kevin O’Donoghue, chief of defence materiel, says that with immediate effect “the default position is that no business cases are to be put to the approving authorities for approval”.