King Charles and Prince William face £10m energy upgrade bill for estates

New rules could affect nine in 10 rental properties in duchies of Cornwall and Lancaster and at Sandringham

King Charles and Prince William could be forced to spend up to £10m upgrading hundreds of rental properties on their private estates to meet planned energy-efficiency rules.

The government has announced that landlords will need to ensure their properties have energy performance certificate (EPC) ratings of C or higher by 2030 – up from the current requirement of an E.