The police force is a giant in data collection, embracing an ever increasing number of sources from driving licences to DNA to Transport for London’s Oyster card payment system and its numberplate identification collected as part of the congestion charge.

The diversity of sources highlights the debate about information sharing that Richard Thomas, the information commissioner, sparks again on Monday. As companies and public authorities collect an increasing amount of our personal data, so concerns are increasing about the accuracy of that data and the way they are used and shared.

Companies are driven to share information so they can target marketing to consumers, sending personalised messages to mobile phones, selling sharia-compliant products to Muslims and producing personalised magazine covers.

But the data from, for example, a Tesco’s Clubcard – the largest and best-known loyalty card scheme – may also be shared with police for crime detection and prevention purposes. Details typically provided to loyalty card schemes include name, address and family information, such as the number of adults and children in the household.

Tesco said on Monday it would only give information to the authorities when it was required by law to do so.

“We don’t routinely share with any third parties,” it said.

But the admission nevertheless highlights the information commissioner’s point that data are often shared in both the public and private sector without people’s knowledge.

Furthermore, the complex webs of information-sharing relationships that are developing make it increasingly hard for people to assert their legal rights to see what details are held about them.

Mr Thomas has warned that while some data-sharing can be useful, Britons have woken up in a “surveillance society” without debating its emergence.

His argument is not that all sharing is bad, but that there is a low level of understanding among the public about who collects what information.

These kinds of worries are echoed by Michael Parker of the NO2ID campaign, who says there is an “alarming secrecy” surrounding the use of some personal information, particularly that held by companies and with whom they share it.

Others are worried about the quality of data held: the figures might accurately track spending patterns but are slow to update demographic data, such as when people marry or have children, according to Keith Dugmore of consultancy Demographic Decisions.

Mike Savage of Manchester University says databases currently tend to have many misspelt names and can be out of date, for example because they are too slow at removing the names of people who have died to be of full value.

According to an official report published last year, 22 per cent of records fed into the national police computer by one police force, Avon and Somerset, contained errors even though they had been double-checked.

Mistakes are also a concern in business, for example, in situations where credit reference agencies compile data on individuals from a variety of sources. These include public records such as county court judgments and electoral roll data.

They also include the identity of people with whom the subject has certain joint financial obligations, such as a mortgage or credit account.

If such information is wrong it could mean people are wrongly denied access to credit.

Stephen Sklaroff, director-general of the finance and leasing association, told a parliamentary committee in June that the industry was very concerned about improving the quality of its data and had put more effort into making sure they were captured and transferred in a way that was less prone to error.

All this is leading to calls among some privacy specialists for greater openness, stronger legislative protection and for people to think twice before providing their personal details.

Companies say there are strong commercial – as well as legal – pressures for them not to misuse information. They say individuals’ worries about sharing are unfounded, as personally identifiable data are not sold on to third parties, and information is shared with law enforcement authorities on a strictly controlled basis.

It is a debate that is sure to intensify as the sophistication of information gathering increases still further.