Piccadilly Line: Severe delays between Acton Town and Uxbridge / Heathrow Airport and between Arnos Grove and Cockfosters. MINOR DELAYS between Acton Town and Arnos Grove due to a signal failure at Acton Town and an earlier faulty train at Hyde Park Corner. Tickets will be accepted on London Buses. Severe delays due to a signal failure at Acton Town and an earlier faulty train at Hyde Park Corner. London Buses are accepting tickets.