How to find yourself a bona fide hermit to roam your garden was a problem besetting many a well cultivated person with an eye for the Romantic during the 18th century.

Many such people, having employed landscape architects to construct water grottoes or caves, then felt a compelling urge to find a hermit to live in them.

Some even took to advertising in newspapers — though such action apparently gave rise to lively dinner party debate about whether a proper hermit would be likely to take a daily newspaper.

Water grottoes first made their appearance at water sources in Britain in the early 17th century, but became progessively more fashionable over the next 150 years or so, as William Kent’s work at Rousham, for instance, illustrates.

The owner of Rousham House, Charles Cottrell Dormer, tells me — disappointingly enough — that there never was a hermit employed there as far as he knows. Nevertheless, perhaps the most extraordinary water gardens, complete with perhaps the most extraordinary hermit ever, existed not far away in Enstone.

Thomas Bushell, one-time secretary to the Lord Chancellor, Francis Bacon, created the Enstone Marvels there. These were water gardens, near where the Harrow pub stands today, which were so marvellous that King Charles I and Queen Henrietta Maria visited them on August 23, 1636.

Dr Robert Plot (1640-1696), first Professor of Chemistry at the University of Oxford, and the first keeper of the Ashmolean Museum, described the event in his 1677 Natural History of Oxfordshire: “a Hermite [who rose] out of the ground, and entertain’d them with a Speech; returning again in the close down to his peaceful Urn. Then was the Rock presented in a Song answer’d by an Echo and after that a banquet presented also in a Sonnet”.

The rock in question was “so wonderfully contrived by Nature herself, that [Bushell] thought it worthy all imaginable Advancement by Art.” Indeed the Queen graciously allowed the rock to be named after her.

She did this after watching two fountains of rose-coloured water rise into the air, each suspending a golden ball. The king helped himself to one of the balls and found inside it a portrait of the queen carved in ivory.

Dr Plot laments that during the Civil War (“the late unhappy wars”) the garden “with all the ingenious contrivances about it” fell into decay.

Mr Bushell, however, was apparently an eccentric of the first water. Long before he contrived his Enstone Marvels he went about in a coat entirely covered in buttons, like a sort of pearly king; and when Francis Bacon fell from favour, Mr Bushell took himself off to the Calf of Man, a small island off the Isle of Man, and became a hermit in earnest, living on herbs.

He wrote: “The sudden fall and death of my late Lord Chancellor Bacon, in King James’s reign, were the motives which persuaded my pensive retirements to a three years’ unsociable solitude in ye desolated isle called the Calf of Man, where in obedience to my dead lord’s philosophical advice, I resolved to make a perfect experiment upon myself, for the obtaining of a long and healthy life.”

Better times did befall him. A graduate of Balliol, he was an expert in mining and in minerals, and Charles I put him in charge of the Royal Mines of Wales, in which capacity he minted money and sent it to the king in Oxford.