His announcement was followed by a message from the US special presidential envoy for climate, John Kerry. This year's ceremony came just weeks before the UK is set to host COP26, the world's most important climate summit. The next Earthshot Prize ceremony is set to take place in the US in 2022, Prince William said at the end of the event.
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Some historians have suggested it was the massive military spending of the Second World War, after the US belatedly entered in 1941, that finally put the Great Depression to bed and laid the foundations for the late 20th Century superpower.
The scheme unveiled by Mr Johnson today promises around £5billion in new money - albeit for country smaller in geographic size and population.
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