'Reversal of fortunes' for weather
Temperatures are set to fall across much of the country in what the Met Office has described as a "reversal of fortunes".
Much of Britain sizzled on the hottest day of the year so far, with 25C (77F) recorded at St James's Park in London.
But those who benefited from today's heat may not be so lucky tomorrow, with parts of the country set to see a 10C drop.
Meanwhile in areas which did not get above single figures today, like the coast of Wales, temperatures could get up to 8C warmer.
A spokesman for the Met Office said: "Areas that were cooler today will be a little bit warmer tomorrow. But in the south east, where we saw highs of 25C (77F), it will be up to 10 degrees cooler. A real reversal of fortunes."
At its peak today, parts of London were hotter than Athens, Rome, Nice and Ibiza.
Sun worshippers enjoyed the unseasonably warm weather, flocking to beaches in Brighton, Bournemouth and Devon, while scores soaked up the rays in London's parks.
The London Fire Brigade attended a reported sighting of a man under the water at the male bathing pond in Hampstead Heath but a search failed to locate him and the incident was handed over to the police.
And in Surbiton, south-west London, police were forced to smash the windows of a car to free a baby, after the driver accidentally locked her keys inside. The child did not require medical treatment.
Meanwhile train travellers faced hot and sticky journeys home across the country due to a series of problems.
There were long delays to services in and out of Brighton due to the derailment of an empty train that was coming out of the depot at the Sussex station.
The problem affected passengers with the Southern train company which was also experiencing delays due to a signalling problem which was holding up services between Eastbourne and Hastings.
Another signalling problem, near Feltham in south-west London, led to delays between London and Reading/Windsor and Eton Riverside. Services from Feltham towards London via Twickenham were not able to run.
London Overground passengers were held up after a vehicle struck a bridge at Camden Road in north London.
Temperatures were so high that Network Rail were prompted to monitor train tracks for signs that the rails may have expanded and reduce the speed of their trains.
A spokesman for the rail company said it was forced to lower the speed of trains slightly in some areas to reduce the risk of the rails buckling.
He said: "Hot, sunny conditions can cause the metal rails to expand as they warm up, which is why we closely monitor track temperatures and take action, if it's needed, to keep trains running safely and reliably.
"Most often these result in slight lowering the speed of trains in just a handful of susceptible areas but in most cases, as today, these are so marginal that they cause no impact on the effective running of the timetable.
"There were no delays to services as a result of the weather today."
The highest April temperature on record was 29.4C (85F) on 16 April 1949.
Nevertheless, bookmaker Ladbrokes has cut the odds on this being the hottest April on record.
Spokeswoman Jessica Bridge said: "The weather might be grim up north, but with the thermometer soaring down south we've been forced to slash the odds in half that April's officially a sizzler."