It all began when the Oxford writer let his passion for hedgehogs run away with him in his book A Prickly Affair.
He boldly declared that “the hedgehog was the most important species on the planet”.
Hugh Warwick, from Florence Park, knew he was asking for trouble making such a sweeping statement.
Sure enough, wildlife enthusiasts from across the nation were soon taking issue with his claim.
He was made well aware that there were others equally obsessed with water voles, badgers and owls, to name but a few.
So the idea of a new book The Beauty in the Beast about Britain’s favourite creatures, and the people who love them, was born.
But as well as introducing fascinating and often eccentric characters, Mr Warwick decided to make things really interesting by putting his neck – or at least his leg – on the line.
He would draw up a shortlist of enthusiasts and write chapters on each of them.
And then at the end of the book he would reveal the one that had done most to win him over and have the winning creature tattooed above his ankle.
Mr Warwick, a father of two who already has a tattoo of a hedgehog, went off in pursuit of a man reinstating beavers in Scotland, an adder expert in Norfolk and a dolphin researcher at work in the North Sea.
And Ivan Wright introduced him to the joys of observing solitary bees in Oxford.
His data revealed Shotover to be a hotspot for bees and one of the best sites in the county, with 99 bee species, allowing him to argue for improved protection for the area.
Mr Warwick found a keen advocate for the robin in Dr Andrew Lack, of Oxford Brookes University, who inherited his love of the bird from his father David Lack, a former director of Oxford University’s Edward Grey Institute, who is credited with developing the science of ornithology.
But as Mr Warwick’s new tattoo testifies, the toad won. So why was the Oxford writer seduced by the humble toad – a creature usually considered an outcast and linked to stories of portent or doom – rather than the likes of otters, dragonflies and badgers?
It was the toad’s “ability to change, and the cryptic beauty that lies beneath the unbecoming skin” that helped swing it.
The toad’s marvellous advocate was Gordon MacLellan, an environmental educator who follows a shamanic spiritual practice.
The tattoos are already a staple in Mr Warwick’s lectures to groups and schools – not so much an emblem of a midlife crisis as a reminder that the hedgehog man of Oxford, compared with some, is normal.
The Beauty in the Beast is published by Simon & Schuster at £14.99