Train passengers have been warned to allow extra time for their journeys today after issues on the Chiltern Railways network.
The railway company reported a signalling fault on the line between Aylesbury and Amersham.
This means trains between Aylesbury and Marylebone have been cancelled with some eastbound services being diverted via Beaconsfield.
Chiltern Railways said the 09:06 London Marylebone to Oxford due at 10:28 has been cancelled.
The 10:49am Oxford to London Marylebone train due at 12:16 has been cancelled due to crew being delayed by service disruption.
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