National Rail have said there is disruption on some Southern, Thameslink and Overground routes this morning.
Highbury & Islington / New Cross Gate and West Croydon are facing delays on the London Overground, Southern services are also delayed between London Bridge and London Victoria / Streatham Hill / Norwood Junction / East Croydon / Sutton / Epsom / Purley / Caterham / Uckfield / Eastbourne / Littlehampton / Bognor Regis.
Thameslink is also facing delays between Bedford and Gatwick Airport / Three Bridges / East Grinstead / Horsham / Brighton, between Cambridge and Brighton, between West Hampstead Thameslink / London St Pancras International / London Bridge and East Grinstead, between Peterborough and Horsham, between London Bridge and Three Bridges, and also between Luton and Gatwick Airport / Three Bridges.
They’ve said there is a fault with signalling system at Brockley means trains have to run at reduced speed on some southbound lines. Trains running between New Cross Gate and Crystal Palace / Norwood Junction may be cancelled, delayed by up to 20 minutes, revised, or diverted.
London Overground services are running normally between Highbury & Islington and Crystal Palace.
Disruption is expected until the end of the day.