There are eight Tornados in the RAF force taking part in the US-led coalition against Isis

Tornado bombing missions against Islamic State were temporarily halted yesterday after two missiles fell off one of the ageing aircraft on landing.

The incident came as the head of the military warned that Britain’s fast jets were operating at the “very limits” of availability and capacity.

General Sir Nicholas Houghton said that the Royal Air Force, which has just seven fast jet squadrons compared with 30 at the end of the Cold War, was “challenged” to cover the full spectrum of defence roles required by the government.

He indicated, however, that a possible expansion of aircraft numbers should be considered as part of a review of defence and security that is due to conclude in the autumn.

The strategic defence and security review (SDSR) is