Piccadilly Line: No service between Northfields and Heathrow Terminals and SEVERE DELAYS between Acton Town and Northfields while we fix a signal failure at Hatton Cross. Tickets are being accepted on London Buses, Elizabeth line and South Western Railway services. SEVERE DELAYS between Acton Town and Cockfosters westbound only due to an earlier faulty train at Hyde Park Corner. GOOD SERVICE on the rest of the line.