The National Land and Property Gazetteer (NLPG) database will underpin the National Land Information Service (NLIS) - an online one-stop shop for property conveyancing, allowing land and property searches.
However, sources close to the NLPG project have raised concerns over the quality of address data which is being fed in to the national address database. One supplier, who worked with local authorities and the three suppliers responsible for the NLIS hub, said up to 20% of data in the NLPG could be inaccurate.
Leaders of the NLIS project, which was launched last year, claim that it would allow land and property searches, in minutes rather than days or weeks under the current, paper-based system.
A joint initiative between central and local government, NLIS was the lead service of an Information Age Concordat, outlined in a statement signed by key central and local government figures including the lord chancellor.
A growing number of other key government projects, including the electoral register, will use the NLPG and the police and utility companies are also understood to be considering using the address masterfile.
Each property in the NLPG is supposed to have a unique property reference number. Local authorities must first create their own local gazetteer by merging different address data sets - including the electoral register and council tax records.
Anomalies are supposed to be eliminated by the council. The local gazetteer is linked to the NLPG, by Intelligent Addressing, the supplier which is overseeing the creation of local gazetteers.
But another supplier told Computer Weekly that one of the main problems occurred when properties were duplicated in the national list - each with a unique property reference number - and listed in different localities.
This could result in a property surveyor acting for a customer missing a planning application affecting the property because the house appears in the wrong area. It could also waste time for solicitors and property professionals using the pay-as-you-go NLIS search facility.
One IT professional responsible for creating an NLPG-linked local gazetteer, echoed these concerns and claimed that up to a quarter of its address data was probably not accurate.
Council documents, seen by Computer Weekly, show that more than 10%, some 41,000 council records, listed streets that were not present in the national street gazetteer, which is maintained by Ordnance Survey.
Intelligent Addressing said it achieved a 97% match rate when it compared the entire NLPG to land registry records, which are based on the Postal Address File.
The company declined to show the results of the survey. Its chief executive Michael Nicholson said councils may be left with unmatched address data after the creation of the local gazetteer, but the data in the NLPG was still overwhelmingly accurate. He also said a small number of duplicated address data within the NLPG was inevitable, but this would only be in the hundreds of thousands.