HMS Queen Elizabeth and HMS Prince of Wales were officially estimated to cost £4bn when announced in 2007 The cost of building two new aircraft carriers for the navy, which has already risen significantly because of delays, has soared and could eventually total as much as £7bn, it has emerged. The latest increases are largely the result of a decision in last year’s defence review to equip HMS Prince of Wales, the second of the carriers due to enter into service by 2020, with aircraft catapults and traps. The first carrier, HMS Queen Elizabeth, will be mothballed when it is completed, leaving Britain without a carrier able to take aircraft for 10 years. The carriers were officially estimated to cost less than £4bn when they were announced in 2007. The estimate rose to £5bn last year after the Ministry of Defence decided to delay the construction programme to put off costs. Short-term savings led to cost increases in the longer term. “Cats and traps” will enable the Prince of Wales to be equipped with the naval version of the US Joint Strike Fighter, cheaper than the hugely expensive short take-off and vertical landing version the MoD initially decided to buy. It will also mean that British and French planes could land on each other’s carriers, a feature outlined in the British-French defence co-operation agreement signed last year. The new estimate that the two carriers could now cost £6bn and possibly £7bn is believed to have been suggested by the makers, the Aircraft Carrier Alliance consisting of BAE Systems, Thales and Babcock. The MoD said: “The conversion of the Queen Elizabeth Class will allow us to operate the carrier variant of the Joint Strike Fighter that carries a greater payload, has a longer range and is cheaper to purchase.” It added: “Final costs are yet to be agreed and detailed work is ongoing. We expect to take firm decisions in late 2012.” Critics of the defence review argue that the Ark Royal and Harrier jumpjets, scrapped last year, would have given Britain much cheaper options over Libya than the Tornados the RAF is relying on for air strikes. The government argues that the Tornados can carry more modern missiles and have a greater range. Military Defence policy Richard Norton-Taylor guardian.co.uk