The Ministry of Defence (MoD) has been strongly criticised by MPs over the "flawed" decision to switch fighter aircraft for the Royal Navy's new carriers .
It was announced in the 2010 Strategic Defence and Security Review that the Government would adopt the carrier variant of the US-built F35 Joint Strike Fighter rather than the "jump jet" version chosen by the previous Labour government.
Ministers argued that the carrier variant was a more capable aircraft and that it would increase "interoperability" with other navies - even though it meant mothballing one of the two carriers on grounds of affordability.
However last May, Defence Secretary Philip Hammond announced the MoD was reverting to the jump jet version amid fears the costs of fitting the necessary catapults and arrestor gear - "cats and traps" - were spiralling out of control.
In a highly critical report, the Commons Defence Committee said the 2010 decision to go for the carrier variant was a mistake which led to increased costs and further delays to the carrier programme.
"It is clear that the decision was rushed and based upon incomplete and inaccurate policy development. It was taken without the MoD understanding how the change could be implemented," the committee said.
"Perhaps the primary example of how little the MoD understood about this decision is the fact that it was supposed to improve interoperability. This turned out to be incorrect.
"We urge the MoD to learn the lessons of this closed, rushed and flawed decision of 2010."
The committee also complained that the lack of a proper defence industrial strategy put the UK at a disadvantage compared with competitor countries.
It said that such a strategy should combine a commitment to maintain the ability of the UK to act nationally with an understanding of where a level mutual interdependence or partnership with allies is acceptable.