There are delays of up to 40 minutes on trains running from Oxfordshire into London Marylebone.
Chiltern Railways says this is due to problems with line side equipment between Beaconsfield and High Wycombe.
Services from Aylesbury in Buckinghamshire are also affected.
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Staying cloudy with patchy rain tonight. Rain and stronger winds arriving from the West tomorrow evening.
Cloudy and breezy with rain arriving from the west later.
Cloudy and breezy with drizzly rain at times. Rain spreading in from the west tonight.