This could be because of his job. He's an undercover inspector, one of only a dozen in Britain, whose work exposes him to the fury of sadists, psychopaths and organised criminals. Many cruel people - including the perpetrators of a multi-million-pound rhino-horn scam - would like to inflict cruelty on him.
But perhaps he's ill-at-ease for another reason: the subject we're discussing. Cat-ripping. It isn't, whichever way you look at it, a nice subject. If you look at it through the eyes of an RSPCA inspector, it scarcely bears thinking about.
The trouble started a year ago, although nobody could have recognised then quite how troublesome it was going to be. Nigel Shelton, a uniformed RSPCA inspector in north London, was called to a bloody scene in Palmers Green. The decapitated body of a cat had been found in its owner's garden - and, neatly laid on its owner's doorstep, its head.
Such things happen: man's inhumanity to domestic pets knows few limits. But the curious thing was that a few weeks later something similar happened: a cat's body, also in north London, headless. Then it happened again, and again: decapitated cats began to appear at roadsides and in gardens all over London.
By the end of September, the number of cases was well into double figures, and Paul had been called in. "Basically I work on whatever I'm asked to work on," he says. "But I've a particular interest in anything relating to the occult, and my bosses know that. So once there was a suggestion that it might be ritual mutilation, they asked me to take a look."
Two of the carcasses had by now been examined (on behalf of their owners) by a vet who confirmed that a human decapitator had been involved. Clearly this was some perverted variation on the notorious "horse-ripping" epidemic that has plagued southern England for the past decade. As for the satanic element: "There was one where the cat had been skinned, pinned to the floor of the garden, and they'd made a wooden arrow pointing at the owner's door," says Paul. "That's a satanic thing. Usually they choose a solid family of Christian church-goers."
The shadow of a cloud passes over the room - in an undisclosed place, at an undisclosed time - where Paul is guiding me through two huge lever- arch folders which are groaning with vile detail, photographic and documentary, of horse-ripping, satanic ritual and the London cat-ripping outbreak. The detail includes a satanic "church calendar" which lists the kind of observances required for different ceremonies: animal sacrifice is called for at full moons (the most recent one was on July 28) and on the Great Sabbat (today). The detail also includes horrifying statements by children who claim to have been caught up in satanic rituals; and close-up images of ripped cats, blood-matted fur prised away to reveal gleaming pink internal organs. If you're tempted to see something comic in animal mutilation, a look at some of these pictures would persuade you to take them seriously.
The RSPCA certainly did. All winter, the savage incidents piled up, like a bad episode of Inspector Morse; and, all winter, Shelton and his colleagues worked round the clock to track down the mutilators. A special squad - Operation Obelisk - was formed with the Metropolitan Police. Every call relating to such incidents was meticulously logged, and plotted where appropriate on a map which now showed two distinct but converging clusters: around north London and around south London.
On the basis of tip-offs from the public, the team assembled profiles of four possible suspects, the most solid of whom was a taxi-driver. No firm evidence emerged to link any of them - or anyone else - to the mutilations. But no one doubted that it would. The killer's known modus operandi was so bizarrely idiosyncratic - the missing brains, the drained blood - that he was bound to give himself away eventually.
By November, Operation Obelisk was investigating the suspicious deaths of 39 cats and 10 rabbits, and the coloured stickers on the incident map of Greater London and the South-East were so tightly clustered that it was hard to fit more on. In desperation, the RSPCA issued a press release appealing for information. By December, the number of reported cases had doubled.
Not all of these represented freshly decapitated cats. Some people called to voice suspicions relating to long-past events. None the less, the caseload mounted, as did the general sense of alarm.
The RSPCA advised pet-owners to keep their animals indoors. Roger Gale MP, chairman of the all-party group on animal welfare, announced that "the public can help enormously [by] looking out for these killers and helping to track them down" and called for Crimewatch to get involved. An east London property company, Perryfield Properties, offered a pounds 1,000 reward.
When letters purporting to be from the Cats Protection League began to be delivered to homes in affected areas, claiming that the killings were a form of "Jewish blood sacrifice", the pressure to find the real culprit redoubled. Gradually, the sense of proportion that had characterised investigations began to evaporate. Officers involved in Operation Obelisk spoke publicly of "organised killing" and of the killer "travelling round the capital looking for victims". Newspapers, including this one, reported on the case. "Ritualistic killers stalk family pets," warned one paper. The killer was "believed to be" both "a crazed teenager" and "an organised gang". "The killer must be caught," said Angela Smith, MP for Basildon, adding: "The perpetrator or perpetrators are dangerous people."
A forensic psychiatrist, Susan Hope-Borland, suggested that: "This is someone with a great deal of pent-up anger. There may have been some kind of sexual or violent abuse in their childhood." Indeed, there was so much talk about the link between extreme violence against animals and extreme violence against humans that a West Country lawyer and animal rights campaigner, Chris Fairfax, organised an international conference on the subject.
That conference was to have taken place in April this year, at the Royal Festival Hall. It didn't, largely as a result of an unforeseen circumstance: in February, Operation Obelisk was called off.
There was no formal announcement, but journalists who had been assigned to cat-ripping duties were quietly informed that the alarm was over. With a couple of possible exceptions (including the still unsolved mystery of the skinned cat with the arrow by it), the cats in question had not been tortured by maniacs. They had been killed by cars and then mauled, after death, by foxes.
If the bemused journalists were unsure if this was good news or bad, their editors had no such doubts: this was good news, to be confined, if published at all, to a couple of paragraphs on the inside pages. And so, for sharp-eyed readers, the mystery of the mad mutilators reached its conclusion.
Except that it didn't. You can't whip the public into a frenzy of wild imagining and then expect it to return to earth at a moment's notice. Three months later, many cat-lovers still feel - if not robbed, exactly - somehow shortchanged by the story's anti-climactic ending.
"It was such a glib explanation," says Chris Fairfax. "Suddenly everything's all right - it doesn't ring true to me."
"It's an absolute load of rubbish," says June Bailey, a Sussex-based "pet detective" who helped the owners of several of the non-existent cat- ripper's victims. "An animal, if it gets run over, would not be beheaded, have its legs and heads chopped off and be returned to its garden."
The RSPCA dismisses such doubts out of hand. "I stood at the shoulder of the professor who did most of the post-mortems for us," says Paul, "and he showed me the little serrated teeth marks, even in a couple of cases where a vet had said it was definitely done with a sharp instrument. Once you know what to look for, you can't miss them. The foxes bite off the heads and eat the brains because the brains are the most delicious bit."
The professor in question - an authority on foxes - refuses to be identified. Like many academics, he's wary of animal-lovers. But another leading fox expert, Dr Phil Baker of Bristol University, confirms when asked that: "If a fox found a cat in the road it would certainly pick it up and take it away and then chew the head off." What that doesn't exclude is the possibility that there are also human beings out there who, for whatever reason, might sometimes do something similar.
The RSPCA is keen to discourage such speculation. ("Why do you want to write about this?" asks a spokeswoman crossly. "The inquiry is over.") But part of the organisation's difficulty has been that, as Paul puts it, "We didn't want people to go against foxes." That's meant emphasising, in any public statement, that the foxes only mutilated cats that were already dead. It has also meant keeping public statements to a minimum. And so six months of inquiry, costing tens of thousands of pounds and provoking several acres of newsprint, have mysteriously vanished, hurried from sight to avoid embarrassment.
But some of the issues raised by Operation Obelisk refuse to go away. For a start: if the animal-loving public is really likely to turn against foxes on the grounds that foxes attack domestic pets, the animal-loving public needs its head examined. Attacking pets is what foxes do (when they're not attacking other animals, or chewing the heads off roadkill). Extrapolating from the most authoritative survey we have on urban foxes (carried out in Bristol), it's possible that as many as 7,000 cats a year are taken by foxes in Greater London alone - and a considerably larger number of pet rabbits and guinea-pigs. That's excluding traffic accidents. If it comes to that, another study has suggested that, each year, more than 100 million birds and small animals in Britain are tortured and killed by domestic cats. Animals can be absolute animals.
People, by contrast, can be pig-headed and woolly-minded, especially when they suspect that a public organisation is trying to lead them by the nose.
"The RSPCA put forward these ridiculous notions because they can't find out who's done it," says Bailey. "They don't want to spend any money. But it's still going on. There are a lot of rabbits missing in Portsmouth at the moment, and there's an awful lot of cats gone in Sussex. I don't think it's satanists, but it is ritual slaughter."
"It sounds like a cover-up story to me," says David Cayton, a UFO investigator who is currently looking into an "epidemic" of animal mutilations around Britain, "because it's not the sort of thing that the authorities want the general public to know about." Cayton believes that such mutilations, together with crop circles, "show that we are being visited by advanced beings from other worlds". He recently engaged the services of a professor of pathology to help him in his quest for "tangible evidence", but has so far come up with nothing conclusive.
Even Fairfax, an intelligent and down-to-earth man, is reluctant to give up the possibility of an unnatural explanation for the London cat-rippings. "You keep getting these reports of cats going missing," says Fairfax. "And when you see what people do to other people, I have little doubt that there are people out there who take great pleasure from mutilation. There are some fairly scary people out there."
No doubt there are; but what is hardly less scary is the enthusiasm with which everyone - investigators, media, public at large - embraces such conclusions. Have we really become so credulous, and so hardened to the obscene, that a serial killer or a deranged satanist or alien seems the most natural explanation of something that is already perfectly natural? I suspect that we have. Faced with the suggestion that our fellow men have been mutilating pets for pleasure, we conventionally respond: "I can't believe it." In fact, we can't disbelieve it. Somewhere along the line, a "sicko" has to be involved.
"I've no doubt that this sort of thing goes on," says Paul, who also confesses to an interest in UFOs. "There were certainly one or two cases that we looked at where something suspicious was going on. And I've read that there's between 40,000 and 100,000 satanists in Britain." Maybe he's right. But not everything you read is true; and, the deeper you venture into the territory of the Unexplained, the more truth is swamped by credulity.
In America, an exhaustive, year-long investigation of animal mutilations by ex-FBI agent Kenneth Rommel conclusively debunked the "mystery" nearly 20 years ago. That hasn't stopped animal mutilation ("mute") becoming an established sector of the paranormal industry there. Outbreaks of cat- ripping come and go like clusters of UFO sightings. Recent years have seen cat-ripping scares in Vancouver, British Columbia; Lee, New York; Plano, Texas; Falls Church, Virginia; Ahwatakee Foothills, Arizona; and Los Alamos, New Mexico, where cat-owners were warned by police to keep their pets indoors. In several cases, road accidents and coyote maulings were subsequently declared responsible; but those who follow these matters view any such declarations with deep distrust.
In Britain, the London cat-rippings are already becoming established in the hearsay archives of the Unexplained, and those who insist that they were explained are liable to be dismissed as Establishment stooges. Indeed, Paul himself has already fallen out with at least one valued contact by ruling out alien abduction as an explanation for missing pets.
In an ideal world, the RSPCA would discourage the development of a British "mute" industry with a more high-profile campaign, But, as Paul says, "The last thing we want is for our officers to think every time they take a call about cat mutilation, `Ah, they're just foxes or RTAs [road traffic accidents].' People are cruel to cats."
Come to think of it, in an ideal world, the RSPCA would have been able from the outset to identify fox mutilations; and one of the two vets who examined carcasses before the anonymous professor was called would not have made what Paul calls "a couple of errors". Yet it would be facile to mock those involved in Operation Obelisk for their misplaced zeal. When Nigel Shelton suggested that the killer was "someone who organises his attacks with precision, working mainly late at night or early in the morning", he wasn't far from the truth; and, as he points out today, "The information we received about what people suspect other people of, that wasn't wasted." The RSPCA could hardly have ignored the possibility that the incidents derived from human sadism, and the media could hardly be expected to play down the story when it was fed to them, or the pundits to under-react when asked for comments. That is how modern society works.
The real mystery is how modern society got that way - how we got into the habit of rejecting, with our metaphorical remote controls, all but the most sensational accounts of the world. The media and the movies are clearly parts of the explanation; but so, in this case at least, is a view of the animal world that recalls the worst Victorian idealisations of women.
When Yvonne Trumble, the owner of a "ripped" cat , said that the answer to such atrocities was to "teach your pets not to trust human beings", she was giving voice to a "four legs good, two legs bad" philosophy that, in the age of "stranger danger", seems almost universally shared. Call it mass misanthropy or call it paranoia, it's still misguided. Given the choice of leaving my children in a field with a fox or with a randomly chosen human, I know which I'd choose. But the habit of viewing the human world as a horror movie is a hard one to break; and the odd thing is that, the more you get into it, the more life tends to imitate your dark imaginings. 1
Above right: David Cayton, a UFO investigator who is looking at the `epidemic' of animal mutilations in Britain.
Above: newspaper cuttings reporting on the search for a cat-ripper.
Right: Yvonne Trumble, one of whose cats was killed and mutilated in London last year