Metropolitan Line: Severe delays between Harrow on the Hill and Watford and MINOR DELAYS on the rest of the line following the late finish of engineering work. Trains non stopping Northwick Park and Preston Road southbound only customers are advised to change at Wembley Park. Tickets will be accepted on local TfL Bus services, on London Overground services between Euston and Watford Junction and on Chiltern Railways between Amersham and Marylebone.