Ordnance Survey mapping data should be free from April 2010.
Ordnance Survey map data will be freely available online to everybody from 2010, the Government has announced.
The move will allow people to interpret public statistics about crime, health and education by postcode, local authority or electoral boundary.
Currently, the geographical data is only available free of charge to small scale developers.
Opening it up is key to the success of government plans to free its data via data.gov.uk, say the site's creators.
"Making all that data available doesn't make much sense without the geography to tie it all together," Professor Nigel Shadbolt, one of two Information Advisers to the government, told BBC News.
"Time and place are the two things that make sense of other data. Which hospital, where, when, for example."
The other adviser is Sir Tim Berners-Lee, inventor of the web. He and Prof Shadbolt have been tasked with guiding the Making Public Data Public project.
It is a commitment to make a wide range of non-personal data collected by the government on subjects such as health, crime and education available online for free in a raw form.
Developers can then use it to create mash-ups - a web page that combines sets of data to link up results.
For example, combining the road traffic accident statistics of a certain area with the amount of local vehicle thefts could reveal whether there is a correlation between the two.
The ability to do this by location is crucial, according to Professor Shadbolt. Culturally people are interested in "hyper locality" - what is going on in their street or postcode - he says.
According to Stephen Timms, Minister for Digital Britain, 80% of public sector data mentions a place.
He described the announcement as "an important step" in the Government's public data strategy.
Professor Shadbolt believes that OS maps are more comprehensive in their coverage than other open source competitors which are already freely available online.
Despite this, he thinks that developers have shied away from OS data because of the restrictions on its use - its current free offering has a "fair use" policy which requires people to apply for commercial licenses once their website reaches a certain threshold, and there are issues of over rights.
"If, for example, you built a 'where's my nearest post box' site, and you had more than 200 people a day looking at it, you'd start to hit limits, " OS product manager Ian Holt told the BBC in October.
Professor Shadbolt says that if people could get at the data "they would prefer to use it".
The transition to free-for-all is likely to happen in April 2010 and was announced on 17 November by Prime Minister Gordon Brown and Communities Secretary John Denham.
"We want people to be able to compare the outcomes and the costs for their own local services with the services delivered elsewhere, and suggest means of improving and driving change," said Mr Denham.