The Mayor of London is seeking to become an “interested party” in a legal challenge on Heathrow expansion due to be heard in October.

Sadiq Khan joins the likes of Richmond and Wandsworth in seeking the permission.

The authorities say its crucial they are involved as the case and its outcome has serious consequences for their residents.

Heathrow is appealing a decision by the Court of Appeal earlier this year that ruled the government’s go-ahead for expansion was unlawful.