Metropolitan Line: No service between Chalfont & Latimer and Chesham, and MINOR DELAYS between Harrow-on-the-Hill and Amersham / Watford due to a signal failure at Chalfont & Latimer. SEVERE DELAYS between Baker Street and Harrow-on-the-Hill due to a signal failure at West Hampstead. Tickets are being accepted on London Buses. GOOD SERVICE on the rest of the line.