From the Sitefinder FAQ:
How up to date is Sitefinder?
3, Airwave, Network Rail, O2, Orange and Vodafone, all supply data to Ofcom at approximately 3 months intervals. Because of the uncertainty of whether Ofcom may have to disclose the data under the Freedom of Information Act, T-Mobile has decided not to supply data for Sitefinder, pending the outcome of legal proceedings in the Court of Appeal to determine if Ofcom should supply copies of the Sitefinder data to third parties in future.
Can I have a copy of the Sitefinder Database?
The data within Sitefinder is owned by the mobile network operators, who supplied it on a voluntary basis. It is presented in an agreed format as the underlying data is regarded as commercially and security sensitive. Ofcom does not have the Industry's consent to release either the data or any other derivations from it . We are not, therefore, supplying the underlying dataset to any enquirers. Legal proceedings are ongoing to consider the applicability of the Freedom of Information Act and associated legislation to such network data.