The UK's former top civil servant has re-emerged at independent investment bank Rothschild, his first private sector appointment since his controversial departure from Whitehall in the summer.

Lord Mark Sedwill is set to join the bank in January as a senior advisor, Rothschild said in a statement. He stepped down from his role as cabinet secretary and national security adviser in September after a high-profile spat with Dominic Cummings, prime minister Boris Johnson's former senior adviser.