The Environment Agency has issued flood warnings for areas in the River Wandle's catchment following thunderstorms and heavy rain overnight.

Low-lying parts of Croydon, Sutton, Wansdworth and Merton could be hit by floods, with further downpours expected throughout today.

The agency said river levels remained normal this morning as the volume of overnight rainfall was less than expected.

But it added: "This situation could change throughout the day.

"Further rain is forecast today, with the heaviest thunderstorms likely in the morning.

"Surface water flooding and flooding of low lying land remains possible."

Torrential rain and flash flooding have hit travel in south England after half a month's rain fell in just a few hours.

Schools have been shut, buildings flooded and a train derailed near Watford Junction after hitting a landslip caused by the deluge.

The worst-hit areas are across London and the south-east of England which all have amber warnings in place until 10am, according to the Met Office.

Heavy rain is not forecast for the weekend and the outlook for the next five days is relatively dry, according to the Environment Agency, which said the flood alert for south London would remain in place for the rest of the day.