Engineering works taking place between Harrow-on-the-Hill and Amersham have overrun, closing all lines running between these stations.
As a result, trains are currently unable to operate between London Marylebone and Aylesbury / Aylesbury Vale Parkway, and will be cancelled.
This issue is expected to continue to impact services until 06:45.
Check before you travel:
You can check your journey using the National Rail Enquiries real-time Journey Planner.
Compensation:
You may be entitled to compensation if you experience a delay in completing your journey today. Please keep your train ticket and make a note of your journey, as both will be required to support any claim.