The government is to explore ways of making all Ordnance Survey maps freely available online from April, in a victory for the Guardian's three-year Free Our Data campaign. The move will bring the UK into line with the free publication of maps that exists in the US.

Gordon Brown announced the change at a joint event in London today with Sir Tim Berners-Lee, the inventor of the World Wide Web, who is now information tsar advising on the handing over of private government data to the public.

The government has been inspired by the success of crime mapping where "data openness" is helping citizens assess the safety of geographical areas.

Today's announcement will be followed by a speech, due next week by the chief secretary to the Treasury, Liam Byrne, explaining how the freeing up of data, alongside the scaling back of other functions of central government, could lead to a "smarter state".

The government is moving to open up data after the Tory party first made clear that a key shift in how it would govern would involve passing on information to the public.

In the new year Brown intends to publish 2,000 sets of data, possibly including all legislation, as well as road-traffic counts over the past eight years, property prices listed with the stamp-duty yield, motoring offences with types of offence and the numbers, by county, for the top six offences.

It is thought transport providers, such as train, tube and bus companies, will lose the right to demand a hefty fee from companies such as independent travel websites and firms devising programs for mobile phones, who want to publish such information.

The Guardian's Free Our Data has campaigned for more than three years to persuade the government to "abandon copyright on essential national data, making it freely available to anyone, while keeping the crucial task of collecting that data in the hands of taxpayer-funded agencies".

Other sets of public data currently not freely available include wills dating back to 1858, house values recorded in the Land Registry, maps, and flood-risk data for individual homes.

More broadly, it is thought that if the government relinquished control of other data sets it could save money.

The prime minister said that by April he hoped a consultation would be completed on the free provision of Ordnance Survey maps down to a scale of 1:10,000, (not the scale of a typical Landranger map set at 1:25,000).

The online maps would be free to all, including commercial users who, previously, had to acquire expensive and restrictive licences at £5,000 per usage, a fee many entrepreneurs felt was too high.

Local authorities also spend a lot of money getting access to Ordnance Survey. Swindon recently had to pay the OS £38,000 a year to use its addresses and geographical data, even though it had collected much of the data.

Brown's announcement comes after Ordnance Survey said, earlier this year, that moving to a free model would cost between £500m and £1bn over the next five years. But a separate study, by a team at Cambridge University, commissioned by the Treasury, found that making all OS data free would cost the government £12m and bring a net gain of £156m.

Today the union representing staff at the OS stated that Brown's pledge was in "complete contradiction with the OS's own plans to explore commercial opportunities and find new ways of raising revenue".

Berners-Lee is working alongside Nigel Shadbolt, a professor of artificial intelligence, working at Southampton University. The pair are due to present their report to Brown by the end of the year.

• This article was amended on Wednesday 18 November 2009. We said the Highways Agency has got an exclusive deal with TrafficTV to send video details from motorway cameras to mobile phones. The Highways Agency has asked us to make clear that it does not have any exclusive deals for use of its traffic data. It makes the information freely available to the public directly through its website and provides free access to data feeds and CCTV images to other organisations. This has been corrected.