Sky News:-  Commuters have been warned to expect travel disruption as the UK’s “extreme” heat continues following the hottest day of the year.

Temperatures reached 30.1C (86F) in parts of the country on Monday, with forecasters predicting the mercury will rise even further in the next few days.

Speed restrictions are being introduced on some of Britain’s railways amid concerns that tracks will buckle in the sweltering conditions.

Emergency services have also warned people about the dangers of swimming in open water after a man died and a child went missing.

Divers recovered the man’s body from a lake in Nutfield, Surrey, on Monday evening after reports he had been struggling in the water.

A major search operation is resuming for the missing child who got into difficulty in Westport Lake in Staffordshire.

Before the man’s body was discovered, Surrey Police said it had received several calls reporting that youths were swimming in the lake and “behaving in an anti-social manner”.

The force said: “Bodies of water may look safe, but can hide dangers such as hidden currents, hazardous objects, pollution and cold water shock, which affects our ability to swim and reach safety if experiencing difficulties.”

The Met Office has issued a yellow health alert for heatwave conditions between Tuesday morning and Thursday evening.

The warning, covering the west and northeast of England, means there is an 80% chance of temperatures which could be a risk to health.

Network Rail said it had activated its “extreme weather action teams” across Britain to monitor “vulnerable locations”.

Speed restrictions will be introduced at certain times because slower trains exert lower forces on the track, reducing the likelihood of buckling, it added.

Andy Thomas, managing director of England and Wales at Network Rail, said: “On very sunny days, rails in direct sunshine can be as much as 20C (68F) above air temperature causing the steel to expand markedly and could, if not carefully monitored and action taken, buckle causing travel disruption.

“Our engineers and specialist extreme weather teams are monitoring track-side temperatures and vulnerable locations and will, if necessary, introduce temporary speed restrictions during the hottest part of the day to keep trains running, albeit more slowly than normal.”

South Western Railway said passengers travelling between London Waterloo and New Malden may face delays as speed restrictions are imposed from 11am each day until Friday.