Jonnie Peacock on the ghost of Pistorius, the pain of running – and an engagement ring made from his ankle bone

It might be adding two and two to make five, but something in his tone after mentioning “the jungle, actually” suggests a cat out of the bag. Pressed whether we may see him in the coming edition of I’m a Celebrity... he simply laughs.

But you don’t need to be an entertainment genius to spot that his exuberant personality would make him a huge hit, quite apart from the fact that his own story is rather more extraordinary than that the average reality show D-lister’s.

Winning gold at London 2012

Born in Cambridge, at age five he contracted meningitis, which attacked the tissue in his right leg so severely that it had to be amputated just below the knee. A dozen operations were to follow, but he refused a wheelchair and, once on a prosthesis, played rugby and football “until athletics found me” in his early teens.

He was just 19 in 2012 when he won T44 100m gold – the blue riband event of the Paralympics – as an 80,000 capacity crowd at London’s Olympic Stadium chanted his name. With his signature shock of blond hair, he was the instant poster boy for the Games. Four years down the line, he defends that title in Rio starting with the heats on Thursday 8 September.

“My life didn’t change as much as some might assume,” Peacock says. “In some ways London seems for ever ago, and in others it was yesterday. But also it feels like Rio has suddenly turned up, and before I know it I’ll be on the blocks in Brazil waiting for the gun, and then it’ll be over.”

It still echoes strangely that among those lining up against him at London 2012 was Oscar Pistorius, who eventually finished fourth. Pistorius was then celebrated as the first athlete to compete both at the Olympics and Paralympics. But would shoot dead his girlfriend Reeva Steenkamp only five months later.

Peacock has previously described the Pistorius he knew as “charming”, and was particularly impressed when the South African took him aside just before the 100m final to tell him: “I’m going to say a prayer for you. This is your time.”

Pistorious after his sentencing

These days, however, Peacock questions his rival’s motive. “I’m a bit bemused now,” he admits. “I’m not sure if he was being really nice, or trying to spook me and psyche me out just before we raced. But mainly, of course, my thoughts are with Reeva’s family.”

Meanwhile, Rio is almost here, and Peacock faces a tough field. Moreover, last year he missed the world championships with abscesses on his stump caused by a new blade (the prosthesis he wears for competition). “I definitely wouldn’t say I’m favourite to win,” he says. “At London 2012 my class wasn’t crazily competitive and I was pretty much the only guy going sub-11 seconds. Now there are five or six guys.”

Still, there’s no doubting that he is an athlete for the big occasion. “I run in a lot of small [able-bodied] athletics meets because there just aren’t that many Para meets to compete at,” he explains. “But I struggle to put on a good performance at those. They give me zero nerves, and I love the adrenaline and gladiatorial feel of a big race. So when the pressure is on and a race really means something, I just hate losing and so far it’s come good at the right time. I’m hoping it will again.”

He is proud that the International Paralympic Committee has punished Russia’s state-sponsored doping by banning the country entirely from participation in the Games, unlike the International Olympic Committee.

“It’s good to see the IPC taking a stand on this tough decision,” says Peacock, an advocate of unified sports governance rather than separate groups for disabled and able-bodied. “There’s only one Russian in my event, but others in Paralympics GB are affected far more.”

This time, however, his longtime girlfriend will not be among his fellow Paralympians. Sally Brown competed in the T46 sprints at London 2012, but missed out on selection for Rio and will watch the Games from her parents’ home in Northern Ireland. Peacock hoots with laughter at the mention of the many conspicuously public marriage proposals during the recent Olympics, warding off any suggestion that he might add one more.

“I’ll stop you right there! That’s not happening! I’m only 23 and she’s 21. I’m not one of these people to jump into life when I’m not ready. I’ll wait. Things are going well and let’s just keep it that way. If people are going to stay together for ever, then there’s no need to rush and get it all signed and sealed before you’re 24 years old.” The two have bought a house together in Loughborough, where they train (“Thank God it’s not London, or we’d be in a shoebox”).

Sally Brown at London 2012

He is sweetly self-conscious when asked why she is right for him: “I’m quite picky. There’s always one thing, isn’t there? Things just don’t click. But they do with her. She’s nice and fiery for me, which is fun and makes life interesting. No day is a bore.”

They certainly share the same humour, judging by a tweet of hers from late 2012: “@JonniePeacock has just informed me he is going to make me a necklace out of his bits of bones from his op for Xmas. So sweet.”

“I had these chips of bone floating around inside my ankle, causing grief,” explains Peacock. “The doctor removed them and I have them in a little pot, which grosses her out. So I told her I’d make her a necklace out of them. But it was a joke... although maybe that could be the engagement ring? One of a kind, at least. Nobody else will have one.” He laughs wolfishly.

Without Sally, his downtime in Rio will be spent either on the Xbox (he and Aled Davies, the world record holder in F42 discus and shot, “get through a lot of hours” that way) or getting a taste of the city. “We’ve been told to stay in the Village, but I may try out Copacabana Beach,” he says. “Life is a gift to be enjoyed. Quite often for me, that means eating, especially burgers. If I want one, I’ll have one. I’m not going to stop enjoying things just because I’m an athlete. I love the opportunities I have through sport.”

Including the opportunity to enter the jungle, maybe, after Rio? As Peacock says... we’ll see.