Gary Barlow, Chris Evans, James May and Brian Cox have set off from Lands End in a pink Rolls Royce raising money for Breast Cancer Care.
The challenge will see them driving from Land's End to John O'Groats in a bespoke pink Rolls Royce Ghost.
They want to try and raise £1 million in 24 hours.
More top news
The climate change group are continuing a week of protests calling for the Government to act sooner to reach zero carbon emissions.
Fine and dry weather staying in the West Country for the next few days, staying warm too but change on the way.
Charlie Powell has the latest pollen forecast for the South West.