On a housing estate in Southampton, surveyor Alyson Whiting is painstakingly recording the outline of a curved flowerbed. One of a small army of field workers for the Ordnance Survey, she is using a tablet computer wirelessly linked to a satellite antenna atop a long pole – affectionately known among the national mapping agency’s staff as a “Gandalf stick”.

The agency’s headquarters previously stood on this site, but now red-brick family homes have sprung up. With them have come new roads, new pavements, new addresses. Whiting diligently records the shape and size of them all.

“You do see features and think, ‘I wouldn’t want to have to do that’. Equally, you look at some and think that’s a really nice block to have to survey,” said Whiting, who has been with the agency for nearly 30 years.

It is this combination of digital technology and sheer doggedness that allows OS, as it now likes to be known, to keep up with constant changes to roadways, houses, even pub names. More than 250 field surveyors pound the streets and rural walkways of Britain and feed 10,000 updates a day into the national MasterMap database.

Now the centuries-old, government-owned company could find itself on George Osborne’s for sale list.

Fresh from announcing the selloff of the taxpayers’ stake in the bailed-out Lloyds Banking Group this week – describing it as the “biggest privatisation for 20 years” – the chancellor appears to be in revenue-raising mood. As he prepares to unveil his grand plan for cutting the deficit next month, questions are growing over what else might end up on the block.

OS is certainly a unique asset. Its roots go back to detailed military maps of England’s south coast, ordered as the government feared a French invasion. It expanded into a mission to create an unparalleled map of Britain. Today it is committed to keep track of 460m man-made and natural landscape features across the country.

For the places Whiting and her colleagues cannot reach, OS has two small aircraft that take detailed photographs. At the new headquarters, still in Southampton, Jim King, delivery manager for this remote sensing division, described how cameras collect several pieces of finely detailed information at every spot – each of the 150,000 images taken each year is more than half a gigabyte.

“From 8,000ft (2,400m) up our remote sensing surveys can spot a single wire fence. In remote Scotland that could be important because it could well be one of the only features, so we need to know if it’s still there,” he said.

He sees competitors like Google as a shop window – showing potential customers what mapping can do. “They get people using maps and seeing what there is, but then they see it’s not up to date and they come to OS.”

The agency has to perform the balancing act of preserving its centuries old reputation for meticulousness while becoming a global player in a fast-moving market for data, jostling with startups and dotcom giants. All the while it must convince its government shareholder it can continue to provide a good deal for taxpayers.

The paper maps beloved by ramblers from Land’s End to Ben Nevis today bring in only 5% of revenues. But in a world where smartphones can pinpoint the nearest available taxi and retailers make home deliveries around the clock, location data is big business.

Commercial director Andrew Loveless is the man charged with bringing in the money. The government is the biggest single client, paying the equivalent of some £55m a year for public sector access to OS data and another £20m to the mapping agency in return for it publicly sharing some of its information as OpenData.

Other annual revenues of about £145m come from deals with satellite navigation providers, energy and telecoms suppliers, search engines and insurers who want details about features such as flood plains. The agency also trades on its rich heritage and experience to get advisory work overseas.

“Having 224 years of history gives us an amazing trade craft. Having spent almost £900m on digitisation, going from calligraphy to being totally digital, we have learned a lot of lessons,” said Loveless.

Government revenues

OS said it saves government departments tens of millions of pounds and also returns a dividend to its shareholder, which last year was £21m. But Loveless wants to earn more from commercial partners, and offer a cheaper contract to government.

“My ambition is ‘how do I reduce the cost to the taxpayer?’”

As for threats from competitors, he said OS is not resting on its laurels but that the newer players have a lot of catching up to do.

“We are not complacent. But what we have, it’s so mature, it will take a substantial investment to replicate.”

The kind of detail coveted by OS is something that, for now, satellites cannot capture.

“I make sure that if it doesn’t move, we survey it,” said David Tucker, who manages 45 surveyors in southern England.

Tucker is in his 40th year at OS and has helped collect increasingly detailed information to the point where the organisation now produces datasets on the height of buildings as well as their outline, the roads around them and address details, all accurate to within one metre. Next, OS hopes to use its MasterMap to create three-dimensional maps.

“The map has come to mean more than just a map. It is lots of layers. Like an angel cake,” said Tucker.

Whether this wealth of expertise will fall into private hands remains to be seen. It appears all options are being left open by the Treasury and the Department for Business, Innovation and Skills (BIS), whose secretary of state effectively holds all the shares in OS.

While a spokesman for BIS said the government keeps ownership of all assets under review, the Treasury confirmed that “the management of public assets will be considered as part of the spending review”.

“The government is committed to ensuring the effective and efficient management of publicly owned assets, including assessing options for disposal,” said a Treasury spokeswoman.

“Where there is no longer a strong policy reason for continued public ownership or where there is potential for an asset to operate more sensibly and efficiently in the private sector, the government will continue to look into the potential sale of public sector assets.”

The Public & Commercial Services (PCS) union said there have been indications that the government-owned company model will continue but that concerns remain over the fate of the organisation relied upon by emergency services and local councils alike.

“I would be shocked if coming out of this Spending Review there was a proposal to privatise OS,” said Tony Conway, a PCS officer.

“If there was a sell-off, it is unlikely it would be sold to UK investors. It’s more likely it would go to overseas investors to get their hands on the expertise of our members and the data OS has … It is an extremely proficient and efficient organisation and it would be something that we as a union would fight tooth and nail to keep, that level of coverage and expertise of the national mapping agency.”