More than 100 homes on the British royal estates of King Charles and Prince William are being rented out despite failing to meet the legal minimum energy efficiency standards required of landlords in England and Wales. An analysis by the Guardian of properties on the Duchies of Lancaster and Cornwall (vast feudal-era property portfolios that have paid out over £400 million to the royal family since 2018) and the Sandringham estate found that roughly one in five homes carry an Energy Performance Certificate rating of F or G — below the legal minimum of E that has applied to all private tenancies since 2020. The findings are particularly striking given both royals' well-publicised environmental advocacy, and raise serious welfare concerns, as many of the substandard properties — some lacking central heating and relying on coal fires — are occupied by elderly and vulnerable tenants living amid black mould and draughty, single-glazed windows.