Today the Public Accounts Committee published its report on our new aircraft carriers. The report shows that the government has managed to spend an eye-watering amount of money with no carrier ready until 2020 and without the full number of planes until 2030.

As a member of the committee, I visited the shipbuilding yards to see the work that was being done, and was impressed by what I saw. Workers on the ground are doing well with the majority of work being done on time and budget. Unfortunately, today’s report shows how a lack of strategic thinking in Whitehall complicated the project potentially wasting billions of pounds, reducing our military capacity and potentially jeopardising national security.

In 1998 the Labour government announced that the Invincible Class carriers would be replaced by two larger, more versatile carriers. These new carriers weighing 65,000 tonnes and with a lifespan of 50 years would give us the power to project military resources over a range of 10,000 nautical miles. However, in last year’s Strategic Defence and Security Review, the government took a number of decisions that alter the carriers’ costs and capabilities.

The 2010 SDSR emphasised the importance of the carriers to our national security. Despite this commitment, the government has changed its mind over the type of planes flown from the carriers, producing expensive side effects. This new aircraft requires catapult and trap technology to take-off and land. The technology is untested and will need to be retrofitted, potentially adding billions to the cost of the project.

The 2010 review was conducted alongside the comprehensive spending review, meaning that strategic decisions were taken without knowledge of the budgets involved. As a result the focus of the review was cost cutting and the carrier programme has suffered. Decisions including scrapping the Harrier programme mean that we will be without a carrier for nine years, and short of full capability until 2030. To reduce costs, one of the carriers will immediately be mothballed, leaving us without the ability to keep a carrier at sea continuously.

The MoD claims that the decisions taken will save £3.4bn in future projects. However, this represents only £600m in actual cash savings with the remainder coming from deferring costs. We will not be aware of the total costs from the change of aircraft until December 2012.

Another troubling aspect of this report is the government’s initial refusal to give the National Audit Office access to the relevant documents. This decision was only reversed after sustained pressure on the prime minister from the PAC chair Margaret Hodge and fellow committee colleagues. For major projects like this transparency is essential, especially with the large risks and sums of money involved.

It is a shame that this programme, which could have demonstrated Britain’s military and engineering prowess, is going this way. Short-term decision making and a lack of strategic thinking means we will no longer have the capabilities the National Security Strategy claims we will need. The government should reopen the Strategic Defence and Security Review before it is too late. Government must learn some valuable lessons from this process; I just hope they will not come at too high a price.