Cothelstone was an ancient seat of the Stawel family. In the second half of the 18th century it was the property of Mary Stawel (1726-1780), the sole surviving direct descendant. In recognition of her ancient lineage, George III made her a baroness in her own right in 1760, with the title to pass to her sons from her first marriage to Henry Bilson Legge, Earl of Dartmouth. After the death of her first husband in 1764, Mary married Wills Hill, the Earl of Hillsborough (he would be created Marquess of Downshire after her death).
The tower on Willett Hill tantalises with a glimpse above the trees when approaching by road, before disappearing completely as one begins the ascent on foot – which makes it all the more exciting when after a stiff climb the folly eventually bursts into view.