Britain’s new aircraft carrier HMS Queen Elizabeth will go “straight to the bottom of the ocean” in any future hostilities unless more maritime patrol planes are bought to protect her, retired RAF leaders warn.

In a letter published in Thursday’s Telegraph, former senior officers say that the current plan to buy nine aircraft is not enough and at least three more are needed.

The letter from four former RAF officers with significant maritime aviation experience comes as the new warship costing more than £3bn has recently begun trials in the North Sea.

Britain axed its troubled Nimrod patrol plane programme as part of the 2010 cost-cutting defence review. The Ministry of Defence announced in 2015 that it will order nine Boeing P-8 submarine hunting planes, with the first coming into action to defend the carriers and Trident from 2019.

But the letter signed by Air Marshal Sir John Harris, AVM Andrew Roberts, AVM David Emmerson and Air Commodore Andrew Neal claims that the order is too few to keep a round-the-clock watch on both the nation’s deterrent and its new 65,000-ton flagship.