A Whitehall policy to promote the use of open source software within government will struggle to change the existing 99 per cent of proprietary software now in place.

Open Source Software within UK Government, published by the Cabinet Office this week, spells out key decisions over open source use by the Government, including its intention to "seek to avoid lock-in to proprietary IT products and services".

It promises to consider open source solutions alongside proprietary ones in IT procurements, with contracts being awarded on a value for money basis.

The policy is intended to make the Government less reliant on individual suppliers such as Microsoft.

But it has a long way to go to make any real impact, as open source accounts for just one per cent of the software used in Whitehall.

Douglas Alexander, Cabinet Office Minister of State, said: "This government is intent on securing the best value for money in its IT procurements by encouraging the development of a flourishing IT industry which supplies both proprietary and open source solutions to the public sector."

Other key policy decisions include the possibility of the Government obtaining full rights to bespoke software code, and exploring further the possibilities of using open source as the default exploitation route for government funded research and development software.

It also made a commitment to only use products for interoperability that support open standards and specifications in all future IT developments.

However, a series of parliamentary questions last week from Labour MP Brian White reveals the mammoth task ahead.

The Department of Transport said that less than one per cent of the software it uses is open source, and the Department for Environment, Food and Rural Affairs confirmed that its use is "insignificant in overall percentage terms".

The Treasury explained that there is "minimal" use of open source software at the Inland Revenue, Customs and Excise and the Treasury itself.

The Department for Works and Pensions admitted that open source is not deployed in any of the department's national or mainstream IT systems.

"I hope the [new] policy will increase the use of open source to something meaningful," said White.

"One per cent is not meaningful. Following 11 September, we can't afford to be reliant on a single piece of proprietary software if we are to take security seriously."

The MP suggested that there were fears that the Public Accounts Committee may prevent departments opting for open source.

"You don't get sacked for choosing Microsoft," he said. "Fear leads people to take the easy option. I'm not saying that the Microsoft option is wrong, but there needs to be a balance."

Central government IT spend reached £3.4bn last year and open source supporters argue that this figure could be reduced by considering open source options.

Eddie Bleasdale, director of Linux consultancy Netproject, said: "The problem is not that the Government isn't using open source but that it is totally favouring proprietary software and relying on Microsoft. Laziness has prevented it from thinking outside the box."

He added that using open source software could achieve "massive savings, cutting IT costs to less than 30 per cent" of current levels.