Train users face delays due a signalling failure which had lead to service on two lines being suspended.
Service has been suspended on the Bakerloo Line between Stonebridge Park and Harrow and Wealdstone and there are severe delays on the rest of the line due to a signal failure.
Trains running on London Overground between Queens Park and Harrow and Wealdstone station have also been suspended due to the same signalling problem.
Transport for London say tickets are being accepted on bus routes while engineers fix the problem.
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