Disruption on First Capital Connect between Cambridge and King's Cross, between Peterborough and King's Cross and between Letchworth Garden City and Moorgatedue to overhead wire problems between Stevenage and Hitchin. Tickets being accepted on London Underground and Greater Anglia services.
Shuttle trains run Letchworth - Cambridge, Biggleswade - Peterborough and Welywn Garden City - King's Cross. Buses run Welwyn Garden City - Letchworth / Biggleswade, Stevenage - Hertford North / Luton Airport Parkway.
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John, who began running for Age UK back in the 1980s when he was aged 53, has raised an incredible amount since then - more than £40,000.
It was Tom's second marathon in two weeks run in memory of his father, Martin Campbell.
Surrey Police are appealing for witnesses after the driver was seriously injured in the crash in the early hours of Saturday.