Commuters faced yet more misery today as train services were disrupted by signal problems and flooding.
Lines were flooded between Preston Park, Brighton, and Hassocks.
Connex express trains between London and Brighton were running once an hour instead of the normal twice-hourly service.
Thameslink said its trains were able to get into Brighton from London but services were cancelled in the opposite direction between Brighton and Haywards Heath.
The trains which were running were delayed by as much as 50 minutes as the weather compounded an already difficult situation on the lines.
Connex spokesman Ken Gibbs said: "It is not a happy situation. I'm afraid it is the dreaded floods again.
"The flooding is so severe the water is reaching track level, which means the electrical equipment used for signalling is being affected.
"Railtrack is having to implement special signal arrangements to get the trains through. This is creating a 20 to 30-minute delay."
Delays were made worse by the speed restrictions already in place in the wake of the Hatfield tragedy.
Mr Gibbs said: "We have cancelled some of the Brighton express services so we can deliver a more reliable service."
Trains are also stopping at stations between Haywards Heath and Brighton to pick up customers who would normally get on the Thameslink service.
Mr Gibbs said the company hoped to step up its service in time for the evening rush hour.
Trains are currently running at eight minutes past the hour from Victoria and at 20 minutes past from Brighton.
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