The Duchess of Cambridge will be inspecting fossils, shells, even dinosaur teeth a little later when she visits the Natural History Museum.
On display there, artefacts from millions of years ago. The collection also includes the skull of a lion who once lived at the Tower of London. And a rather popular gorilla.
Liz Wickham had a sneak preview.
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The high of 35C was recorded on a Bakerloo line train between Piccadilly Circus and Oxford Circus at 2pm.
Weather forecasters say temperatures could reach 35C, beating the previous record of 34.6C in the scorching summer of 1976.
After years of political manoeuvring over the future expansion of Heathrow Airport, there has been an important development this lunchtime.