A UK city council has confirmed it is using a new data-sharing agreement to identify and prosecute landlords and tenants involved in illegal subletting, marking one of the most concrete examples yet of local authorities deploying cross-referenced datasets to enforce housing law. By pooling information from council tax records, electoral roll data, benefits systems and short-let platform listings, the council says it can now flag discrepancies between who is registered as living in a property and who actually occupies it, closing a loophole that has allowed unauthorised subletting to flourish largely undetected for years.