Chip is a heterosexual 48-year-old caterer and father of two from the sedate town of Guildford, south-west of London, who spends much of his leisure time as a Rottweiler.
Chip, who wears a £300 ($530) leather hood, is the "alpha" or top dog of his own pack, which includes two gay men, "Oryan" and "Fidget", and two straight women, Chip's wife "Biscuit" and "Pepper", a 23-year-old from Kent.
"It is just a fantastic release," says Chip after he and his wife had spent much of a week-night evening scurrying around the floor of the family living room on their knees and knuckles.
For 90 minutes they had barked, growled, nuzzled each other and fought over squeaky toys while their two teenaged sons kept themselves busy in their bedrooms upstairs.
"I have been interested in puppy play for 15 years and it is amazingly liberating when you get into the headspace of a pup and just act on instinct," says Chip. "I normally need to be responsible and in control all the time, but as Chip I am mischievous and playful and bouncy."
Some pups describe that "headspace" as a form of meditation.
At one stage Chip broke off our conversation to chastise his 18-year-old son for having gone out on a hot day without sunblock. It was a normal parental lecture, except the dad delivering it happened to be wearing a black Lycra bodysuit and a gently wagging tail.
Pepper, who is an "omega" or junior member of his pack, says Chip has become "a second father" to her since she became a pup earlier this year.
Like many pups, she also has her own handler, her flatmate and former boyfriend, Rich, who plays fetch with her favourite toys, rubs her belly when she is a "good" pup, lets her up on the furniture when he is feeling indulgent, and looks after her on public outings.
"Being a pup is calming for her and a joy for me, because I get to just play and have fun instead of worrying about normal problems and pressures," says Rich.
Human pups, or people who like to act like playful puppies, are rapidly growing in numbers and confidence, spreading from the underground world of gay leather bars and bondage into a new and more mainstream "pup community".
Unknown numbers of people around the world like to don dog-like hoods, collars, tails, sturdy knee-pads and leather or rubber suits in private but this new push to broaden puppy play and bring it into the open is being led by Britain, the country with perhaps the world's most active puppy scene.
Organisers claim Britain now has up to 10,000 pups and "handlers", or people who take the protective role of their owners or trainers.
The author of the world's only academic paper on puppy play, Liam Wignall of Sunderland University, says there has been a "fascinating shift from the original emphasis on dominance and submission towards a new focus on fun and escapism.
"After a hard day at work they [devotees of puppy play] might come home and put on a puppy hood to get into the 'head space' of just being silly and playing around or chasing a ball," he says.
Once secretive and mainly confined to young gay men, this "lifestyle hobby" is believed to have started as a form of sexual domination in either Germany or the United States.
Evolving to place a stronger emphasis on non-sexual fun, it has gained new adherents, thanks largely to online networks and a greater social acceptance of "kink" and fetishes, and in the past few years it has also gained some prominence at public events such as Pride marches.
Dr Jamie Lawson, an anthropologist and teaching fellow at Bristol University, is the author of a new research project "trying to understand more about this behaviour and what people get out of it. It involves casting off your humanity and surrendering some power by giving up things that make you human, like speaking, walking on two legs and even being able to use your hands," he says.
"The question is 'why would they do this?' The simple answer is they enjoy it - but that's actually very complex and is worth looking into."
While many pups decline to be identified, others are quite open. Scamp, or Alex Clark, a 32-year-old bicycle repairer from London and his handler-boyfriend Andy, an artist, are happy to reveal their identities. Scamp says he has been doing puppy play for 15 years, and for six years has often slept in a dog cage in his bedroom.
"I have to tread carefully but the truth is that pup play is completely non-sexual for me. It is about escape and play, because when you are in the headspace you are instinctive and thoughtless; you just act on whatever comes into your head."
"Hexyc", a physics graduate who has just won a job at a London finance firm, says that many of his friends know about his dual life as a pup but he worries that employers and workmates might make harsh judgements.
"I'm open with my friends about it but I'm only 22 and I could regret it later on if I went public."
Hexyc designed his own bright-blue rubber suit. Putting on the suit takes more than 30 minutes and begins with slathering his body in lubricant. Next comes a chest harness, then collar and dog tags, a latex puppy bandana, heavy-duty knee pads and bright green boots.
Finally he needs help to zip on his paws, which lack thumbs. That robs him of a lot of independence, which is part of the attraction for those who enjoy not being in control.
Hexyc says people are attracted to pup play by different things. "For some it is all about sex, for others it is just fun and not at all about sex. For most it seems to have elements of both.
"I would not pretend that there is absolutely no sexual attraction to it for me - right now I am wearing a dog collar and a rubber suit, after all - but I mainly do it for fun. It is about being silly and affectionate, enjoying unconditional love and not having to think about all the things that worry human beings."
Public appearances can be awkward, with one experienced pup saying that "older adults and little kids are great but you can get some aggro from teenagers ... and from real dogs."
That was borne out by trips with Chip to a large park near his home and with Scamp, his handler Andy and another pup to a park in Croydon in South London. Bystanders tended to smile quizzically and occasionally shake their heads in disbelief but generally they took a "to each their own" approach.
"They're not hurting anyone," shrugged Andrew, a 51-year-old Canary Wharf bank worker who was stopped in his tracks by the sight of Andy and his pups.
Several real dogs - called "bio-dogs" by human pups - barked madly at Chip, who has perfected many of the growls, postures and other mannerisms of a dog.
Kye Etherton, a London-based web developer who says he puts 40 unpaid hours a week into running the social network puppypride.co.uk, says his network alone has 1500 UK-based members and estimates there are up to 10,000 "pups" in Britain.
Others say that 5000 is a more realistic estimate but the rapid growth in recent years has been evident at the annual London Pride marches.
The US has more pups overall but Britain has the highest per capita participation, Etherton says. There are particularly active communities in Germany, Belgium, the Netherlands and Australia, where a particularly active group is the Sirius Pup Pack. In New Zealand, the pup scene is yet to establish much traction.
The one celebrity of Britain's puppy world is "Zentai Spot", a 32-year-old theatre technician from Hertfordshire, who wears an elaborate full-body Dalmatian suit and was named "Mr Pup UK 2015", the first time the title was awarded.
He got into puppy play 14 years ago through a fetish for skin-tight clothing.
"I used to be the only straight guy at a nightclub event but it is broadening out every day and the growth is coming from the soft side rather than hardcore stuff," says Spot, whose real name is Tom.
Spot's former fiancée, Rachael, says she broke up with him over his pup obsession in 2008 as she was overwhelmed by it but she believes that if it had happened now, with more people to talk to about pup play, she could have coped and their relationship would likely have survived.
"We both regret the break-up now," says Spot.
Some pups do admit to social anxieties and mental health issues but forensic psychologist Dr Vincent Egan, of Nottingham University, says it is wrong to assume that pups need any sort of therapy.
"There is an awareness now that what was once seen as disturbed and perverse can just be people expressing their sexuality or relationships in different ways," he says.
It is about being silly and affectionate, enjoying unconditional love and not having to think about all the things that worry human beings.
While conditions such as paedophilia and sadism are still considered mental disorders, most "kinks" are no longer seen as a result of a disturbed mind, he says. "One generation's perversion is the next's normality. There are people who are neotropic, meaning they go towards trying new things and testing out boundaries in their lives and I think that is a big part of this.
"Some people 'escape' with a glass of red, some kill aliens or chase Pokemon Gos, and some do this. It's a shame people can't be affectionate, playful and silly without having to dress up in a PVC dog outfit, but if that works for them, then good luck to them."
Where are all the New Zealand pups?
Greg Bruce goes in search of New Zealand's pup scene.
The issues in researching a subject defined by words like "fetish", "rubber", "puppies" and "bondage" are many, but from experience I can say they begin in your office when your attempt to visit thehappypup.com returns the message: "Web Page Blocked! You have tried to access a web page which is in violation of your internet usage policy. Category: Pornography."
My editor had told me that the practice of pup play or puppy play - humans dressing up as puppies for fun and/or arousal - was emerging out of the gay bondage scene and into the mainstream. While "mainstream" is a term that can be bent to one's will, the office's internet porn firewall bends for no one.
After hitting this page time after time when trying to access what I have to admit were increasingly suspicious-sounding sites, I took my phone out into the cleansing sunshine and spent a furtive half-hour using my cellular connection, with its lack of worksafe protections.
I put feelers out for pups, without success. Through Facebook, I contacted GPup Alpha, part of the Australian puppy pack Sirius, which I had just read about. I wrote him an email starting with "Hi GPup," but after looking at it for a while, I deleted his name, embarrassed, and just went with "Hi."
It didn't matter. GPup Alpha didn't reply and neither did anyone else.
I told my editor I was getting no traction and my next step would be to go and ask around some sex shops. I hoped she would tell me not to bother, but she could hardly have looked more enthusiastic. "Good idea!" she said.
I started at Peaches and Cream Extreme, where I was the only customer. I told the lovely young man behind the counter that I was a journalist interested in puppy play, but I suspect he hears cover stories like that all the time.
It wasn't long before he was showing me a Bathmate Hydromax X30, which retails for $349.99 and is "the ultimate in hydro-technology for penis development and health". Thanks to its new bellows pump system, the Hydromax generates 35 per cent more suction force compared with Bathmate's previous models. The lovely young man told me that one customer had bought the smaller X30 several months ago and had returned recently to buy the larger X40.
He told me Peaches and Cream Extreme doesn't stock any puppy gear specifically and that few people had shown any interest in that type of thing during his 10 months working there.
He told me that in San Francisco, where he was from, animal names were used as codes for fetishes: "A piggy means someone who is open to many fetishes," he said, "as opposed to a mousy type or a bunny type."
I asked if there was a dog code. "Maybe," he said. "I'm sure there's one for cats as well."
He mentioned some other sex shops where I might look for pup-related items, with my best bet probably The Basement, which he described as a sex shop with a gay "cruising lounge" out the back.
Before I went there though, I tried another shop. The people working there didn't want to be named but when I asked them about pups, they said, "You mean pig pup play." I told them no, I meant the mainstream practice of dressing up as puppies in an array of rubber and leather for fun and/or excitement.
They told me no, that I meant pig pup play, which involved people dressing up as puppies and doing things in pig pens that were pretty far from mainstream. I asked them for details. They were reluctant. I pushed them for details. I shouldn't have, because they gave them to me.
Next step, The Basement.
The lovely young man at Peaches and Cream Extreme had given me a map showing the The Basement's location, but had said I would probably need to google to find the entrance. That had made me feel slightly uneasy, but when I got to the location on Cross St, there was a very ordinary and professional looking free-standing sign on the street pointing down the driveway. It could just as easily have been pointing the way to a haberdashery.
The owner of The Basement, Donald, seemed wary, but he was good about answering my questions. The shop had a dog mask in stock. It was in a relatively prominent position near the counter and was fairly basic, in black leather, with some stainless steel buttons for attaching the eyemask and the pointy ears, and a light metal chain hanging from the muzzle.
Donald told me that puppy play was different from just dressing up as an animal. "What's the difference?" I asked. "The other thing is more cosplay," he said. "Puppy play tends to be more guys, gay guys," he said.
I told him we were running a story, suggesting that puppy play in Britain was starting to cross into the mainstream. "Really?" he said. "Probably men that want to dress up as a puppy with a mistress would be the way it would happen."
He told me it was normally a submissive type of person who liked being a pup, and they usually came in a pair, with a "trainer". Donald said he would only sell a couple of dog masks each year. "There are not a lot of people into puppy play," he said. "New Zealand doesn't have the population."
I asked if he knew of any puppies. He said he knew a couple. I asked if he would ask them to talk to me. He said no. I asked if he would do it if they were completely anonymous. He said no. "They are completely closeted."
I never asked him about pig pup play and he didn't volunteer any information. I was comfortable with that.