All trains have been cancelled in and out of one of the country's busiest train stations due to severe flooding.
The downpours have caused signals to fail near Liverpool Street Station and commuters now face delays of up to two hours.
Network Rail is investigating but pictures taken inside the hub show scores of frustrated passengers.
But Greater Anglia is desperately trying to recover the services. National Rail says full service will be restored by 8pm.
It says it is offering compensation to any customer whose train is delayed more than 15 minutes. The amount of compensation increases depending on how late the train is. If the train over 60 minutes late you will get a full refund for the cost of a one-way ticket.
Water is seen leak from the ceiling at Waterloo Station, where commuters also face heavy delays.
Videos show a trail of water on the floor in the station.
Flooding has also delayed services on the London Underground's Metropolitan, Hammersmith & City, District and Circle lines.
Victoria, St Paul's and Moorgate stations have also all been affected by today's weather.
Met Office had earlier warned one month's worth of rain would fall today in most of the country, including London.
A yellow weather was issued between 4am and 11pm.
The Met Office warning states: "Fast flowing or deep floodwater is possible, causing a danger to life and some communities may be cut off by flooded roads
"Spells of very heavy rain are expected to move northeastwards across much of England and Wales during Tuesday.
"Whilst many areas will see some heavy rain with 15-30 mm widely, some places may see up to 70 mm, much of this in a relatively short space of time, typically less than 6 hours.
"Thunder and lightning is also possible along with strong gusty winds."
