Lamport Hall is one of Northamptonshire’s nicer mansions. Remodelled in the 1650s by Inigo Jones’s acolyte John Webb, and again by the Smiths of Warwick a hundred years later, it stands serene and resplendent in rolling parkland, the epitome of the English country house.

But Lamport’s fame does not rest on its architecture, lovely though that is. Lamport Hall is famous throughout the world simply because in 1874 its owner, a gardening baronet named Sir Charles Isham, decided to decorate his new rock garden with 150 grotesque little figurines he acquired from Nuremberg. And from this small seed a great British gardening tradition grew: the garden gnome, ancestor of a million capering, cavorting, mooning ornamental aberrations.

“Every garden-maker should be an artist,” declared Vita Sackville-West, who knew more than most about the subject. “That is the only possible way to create a garden.” And every great garden in England from Stourhead to Stowe is a form of self-expression, an attempt to make a dream real, just like any other work of art. But unchecked self-expression can easily lead one up the garden path, so to speak, until before you know it the bucolic dream has turned into a gnome-filled nightmare.

If you need evidence, look no further than Todd Longstaffe-Gowan’s new book, English Garden Eccentrics, where extravagant topiary and equally extravagant topiarists jostle for position with gothic follies, flamboyant fountains and entire menageries of exotic parrots and kangaroos and wolves, sometimes caged, sometimes chained to picturesque rockeries and sometimes stuffed. There is a deep strain of eccentricity running through the gardens of England: so deep, in fact, that populating a Victorian rockery with an army of miniature Bavarian goblins pales in comparison with the antics of the rest of Longstaffe-Gowan’s eccentrics.

At Enstone in Oxfordshire in the 1630s, for example, the royalist vegetarian Thomas Bushell turned a curious rock formation into a grotto (it helped that he was a mining engineer) and installed a formidable array of water-powered playthings: “artificial thunder and lightning… drums beating, organs playing, birds singing, the dead arising”. There were a couple of Egyptian mummies (one a present from Queen Henrietta Maria, no less) who definitely didn’t rise, but who suffered from the damp and went mouldy; and an ancient hermit who didn’t seem to mind the damp, since he was still lurking in his eremitical grotto when a visitor was surprised to come across him in 1663, “an old man of 105 years”.