Commuters from Brighton, Hove and Portslade were being reassured this morning that a normal service had been restored after long delays yesterday (Thursday 1 September).
Thousands of commuters were held up for hours on their journey home after a man climbed under a train and refused to come out.
Train operator Southern promised that services this morning (Friday 2 September) would be back on track.
The incursion happened shortly after 5.30pm yesterday when a 22-year-old man went on to the line and under a Southern train.
The incident at Thornton Heath in south London led to the power being cut off until 8pm, delaying dozens of rush-hour services out of Victoria.
And the delays lasted long after the man had been detained by police and the power had been restored.
The man was sedated by paramedics before being detained by police under the Mental Health Act and taken to a place of safety.
Just over four weeks ago, on Monday 1 August, a water leak caused a landslip which blocked the line near East Croydon Station and disrupted services for a couple of days.
Some suggested that the problems underlined the need for more alternative routes to the coast, a solution that would be helped by the reopening of the Lewes-Uckfield line.
Lewes MP Norman Baker, a long-time campaigner for the restoration of the link, is now a minister at the Department for Transport.
He said: “We need to look at the capacity between Brighton and London. It’s very constrained because of things like the Balcombe viaduct.”
He said that many trains were full and added: “The only way to get more capacity is to get more lines. And the best way and the cheapest way to do that, in my view, is to reinstate Lewes-Uckfield.”
Last month Mr Baker also asked for a review of the handling of an accident and its aftermath on the M25.
The crash led to a stretch of the motorway being completely closed for almost 24 hours, again affecting thousands of drivers, including commuters, from Brighton and Hove.
Separately, Network Rail has published a list of 11 stations that need action to tackle overcrowding.
The lists includes two stations used by thousands of commuters and other passengers from Brighton, Hove and Portslade – Clapham Junction and Victoria.
Network Rail said that measures to reduce congestion should be identified by 2019.