A Ministry of Defence spokesperson responds to a Rusi survey showing that less than a third of defence and security professionals think Britain has an appropriate national security strategy:

"As our operations in Libya have proved, our extensive basing and over-flight rights enable us to project air power around the world with great effect and at very short notice.

"Even if a carrier had been available for the Libya operation, we would still have based Typhoon and Tornado aircraft in Italy.

"Difficult decisions had to be taken to deal with the MoD's financial blackhole but we are moving towards an enhanced future carrier strike capability with the new Joint Strike Fighter arriving at the same time as the next generation of aircraft carriers.

"This is part of £150 billion that will be invested in new equipment over the next decade."