Ambulance crews are struggling to cope in the heatwave as they try to rescue people in "dangerously high" temperatures.
Paramedic Karl Paddison warned that even healthy people can fall foul of hot sun, adding that the London Ambulance Service has to attend to people who have collapsed on a daily basis.
And the the worst effects are being felt by people stuck in lifts, in the capital's Underground, or those who are so burned they have to be admitted to A&E with sun stroke.
After several deaths as people try to avoid the heat - a look at why swimming in quarries and open water is so dangerous.
Heatwave health warnings were issued today as the Met Office declared it was the hottest day of the year so far.
Why cucumbers really are cool and you should keep your phone in the shade to prolong battery life and other fun facts about the heat.