Dorset is sadly lacking in mountains so we picked a coastal walk from the "hard" section of the book. 8.5 miles/ 13.5km - Trig point 666 feet

"Swyre Head is the highest point of the Purbeck Hills and the Isle of Purbeck in Dorset, on the south coast of England. Although not very high, its relative height is such that it qualifies as a Marilyn. The chalk hill is part of the extensive Southern England Chalk Formation.The hill commands extensive views, including west past the Isle of Portland to Dartmoor, and east to the Isle of Wight, as well as north across the Purbeck Hills to Poole Harbour and the other Purbeck Marilyn, Nine Barrow Down. To the west, the folly of Clavell Tower can also be seen.Set back about 800 metres (half a mile) from the coast, the hill is not on the South West Coast Path, but can be reached easily from the villages of Kingston or Kimmeridge.The hill has a trig point marked as 203 metres on Ordnance Survey maps, but a tumulus, now fully grassed over, forms the highest point, 208 metres above sea level."

Book says walk should take 5 hours. We managed it in just over 3.5. BLAM! Take that, Dorset.