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.
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Road closures, rail diversions and widespread flooding is causing chaos across the West Country with Storm Dennis in its second day.
Blustery scattered showers over the South West, and remaining very windy. Storm Dennis is moving away however and away from the region.
Storm Dennis still persisting over the West. Blustery showers and heavy rain continuing through this evening over the region.