Keiran Lee may be one of the most successful male porn stars in the world — but he says when it comes to satisfying his own wife, he can be a flop between the sheets.

The English sex industry stud, who has his 9½-inch penis insured for $1 million, says getting down to business with his wife, Kate, after a long day on the job means he can’t always rise to the occasion.

In an exclusive interview with The Sun Online, he revealed: “At home with my wife I have to apologize, I am pathetic in bed. I’m like a two-minute wonder.”

Lee, 33, whose real name is Adam, has slept with thousands of women and even appeared in all his glory as a giant billboard on Hollywood’s Sunset Boulevard.

But he got into the porn industry by chance — after friends took a naked picture of him on a guys’ holiday and posted it online.

He recalls: “The next thing I know, I was getting emails from people saying, ‘I want you to come and have sex with my wife.'”

“Then a couple from Loughborough asked if I would be interested in making a film. I was about 19 at the time and I was full of hormones, so I thought, ‘I’m going to have sex with a beautiful woman and get paid.’”

“I was working on the railways at the time, and I didn’t really like my job, so I thought, why not?”

The raunchy star’s mom found out about his budding adult film career when she was having a drink in the local pub — but Lee says thankfully she took it in her stride.

He explains: “I said, ‘I am not doing any harm. I’m making great money and I am not taking drugs.’”

“She was fine with it. She tells people I’m an erotic model if they ask. It’s a classy way of saying it!”

When Lee started out, he was earning $180 a shoot, but he can now make around $4,000 a day if he is filming scenes and producing.

His porn work, which started with Killagram in Loughborough, has taken him to Spain, Russia and France.

But it was when Lee arrived in LA, where he now lives, that he became one of porn’s biggest stars.

Speaking about his first scene for Brazzers.com, one of the largest porn companies in the world, he recalls: “I was a patient with a broken leg who got a bed bath from a nurse with a happy ending.”

Lee said the most challenging thing about his work can be the temperature on location.

He admits: “If you are having to film in the cold, it can cause problems for obvious reasons.”

“Once I was shooting in Wales, and it was snowing. I was doing this scene outside in the garden in the snow. I couldn’t feel my fingers let alone my old boy.”

One of the other more obvious issues about Lee’s line of work is needing to “stand to attention” for long periods of time — he says his record is 58 minutes.

“I usually go from start to finish without a break, which is unusual for porn actors,” he admits.

“But I was disappointed when I only got 58 minutes — I was working with four girls and aiming for a full hour.”

So how does he delay the inevitable?

“If I am working with a girl, I start doing multiplication and long division in my head to keep an erection,” he says.

Lee is adamant that porn sets aren’t as sexy as people think.

He says: “Sometimes you can be working on a scene for about three hours, and there can be about 30 people on set.”

“You will see a makeup artist playing on her phone, the sound guy reading a book. It’s not exactly inspiring.”

The red-hot chemistry on screen is not always what it seems, either.

He claims: “A lot of women have boyfriends, they are married, they have kids. I can work with a woman and then when they shout ‘Cut!’ she will go one way and I’ll go the other and never see her again.”

Lee’s nickname with the crew is “Princess,” because of his obsession with grooming — he has Botox, manicures and regularly waxes to look his best.

But he added the pressure of looking good from all angles while filming can often be very tough on the women.

He says: “The girls don’t eat the day before they do certain scenes. They want to be camera-ready.”

“They have to do preparation, which can include enemas. It’s very physical, and they often drink energy drinks to keep them going.”

Lee says he tries to be respectful: “Sometimes I’ve worked with a girl and she has said, ‘I don’t think I can take you, you’re a little too big.’”

“I’m a gentleman, I say, ‘Just let me know, I’ll go slow.'”

As part of his contract, Lee attends sex expos around the world, which can often be an eye-opening experience.

He reveals: “Fans say, ‘I saw you do this scene in 2009, it was fantastic.'”

“It’s funny the amount of men who bring their wives, too.”

“Sometimes the husband and wife will come and the husband will say, ‘My wife loves your work.’ What do you say to that?”

Lee said out of all the countries he goes to, Germans have the most extreme tastes.

He admits: “The Venus Berlin Festival freaks me out. I have seen guys, dressed as women, chained up, a woman dressed in a dominatrix outfit and she is walking with three midgets.

“I just think, ‘I’ll stick with my vanilla porn, this is too crazy for me. I will play the pizza or pool guy.'”

Lee will only do straight porn, but doesn’t mind doing scenes with other men in them.

Performers have to be tested every 10 to 14 days for HIV and STDs and he firmly believes people are more at risk using dating apps like Tinder than he is as a porn star.

He says: “Our tests are very, very advanced. If I was single, I wouldn’t have sex with someone from a bar — that would be more of a risk.”

There is only one thing that will take Lee’s mind off the job when he is filming — his beloved soccer team.

The avid Derby supporter admits he will stop a shoot to watch a game — and his colleagues hate it.

He says: “I drive the crew mad — I watch every game. I even got them to shoot out of sequence, back to front, the other day when we were playing Leicester. I live for them. I am obsessed.”

Lee loves to play soccer himself and used to be on movie star Vinnie Jones’ team of expat Brits in LA.

And he says it was soccer that made him realize how crazy he was about his now-wife, former porn actress Kirsten Price, whose real name is Kate.

He broke his jaw in two places during a soccer game and she helped nurse him back to health.

Lee gushes: “She’s very special. She was practically living with me so I said, ‘Why don’t you just move in.’ And that was it. Being with her is completely different to what I do at work. That’s just my job.”

The pair have been together for nearly six years, and have a 2-year-old son named Max.

Price retired four years ago, and she now organizes the wardrobe for the films Lee produces.

The X-rated star may be having wild sex on screen with some of the world’s raciest performers, but he says at home his life is very “boring.”

He likes to keep his personal and work lives completely separate too, adding: “Adam and Keiran are two different people. At home I am Adam, I love my soccer, I am a normal guy.”

He plans to move completely out of acting and into producing in the porn industry by the time his son is old enough to understand what he does for a living.

He says: “My wife convinced me to have children. Once I got into porn I thought, it won’t be fair on him or her, everyone will look down on them. I just didn’t want my son to get bullied because of the career that I chose.

“But I have never regretted it. I give him the best of everything. My mom was a single mom and she worked every hour that God sent to give me and my sister the best. I want the best start for my boy.”

Lee says the family has a completely “normal” family life — Max goes to boxing and soccer, and they love having people over for dinner.

He explains: “Even our friends in the industry — we look down on people who get out of control. We see women getting their boobs out and flashing at events — they are the ones who give our industry a bad name.

“We had five couples over on Christmas Day, all who work in the industry, and we just had a few glasses of wine and played board games.

“Although I’m sure everyone assumes we would be having a wild orgy!”