Safety systems immediately alerted our train operator after a Piccadilly line train travelling to Heathrow on Sunday was found to have two doors slightly open.
The operator brought the train to a halt, checked the doors and ensured they could be fully closed before the train was taken to the next station where it was taken out of service.
The safety of our customers and staff is our highest priority and the train remains out of service while we carry out an investigation.
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