Big Preview: John Bishop on his talk show In Conversation With...

John Bishop is deducing why people like being interviewed by him.

After all, with a stellar line up for the fourth series of John Bishop: In Conversation With... the Liverpudlian comedian, 51, must be doing something right.

He even managed to secure an interview with David Walliams after he'd turned down appearing on Piers Morgan's "more established" (as Bishop puts it) show.

"There might be an argument to say, 'Well, that's because you're softer on them, or you're nicer on them'," remarks Bishop, who worked in sales until he found fame in middle age with stand-up.

"But I don't think, if you watch the show, that that's the case. I just think that people don't think they're going to get stitched up."

The amiable TV personality adds: "Piers is good at loads of things and his show's been a great success and, you know, fair play to him.

"But I wouldn't want our show to be in competition because I just think we're a very different beast."

The UK TV original series, which airs on W, sees Bishop focus on just one guest each episode, resulting in revealing and intimate chats with a range of people in the public eye (memorable past guests include Jeremy Corbyn, Lindsay Lohan and Katie Price).

This time round, the likes of Paddy McGuinness, Professor Green, Will Young, Ruth Jones and Gabby Logan will be opening up to the comic, about everything from their careers to their childhoods to their mental health.

It was the interview with his "good mate" McGuinness that Bishop found particularly emotional watching back in the edit recently.

The Take Me Out presenter has discussed his twins' autism in the past.

But, as he told his interviewer, he'd never talked about his feelings in as much detail as we will see him do in episode three.

"I watched this show and cried, and said to him, 'Mate, it's really strong'," recalls Bishop.

"And it's not because somebody's cried, it's because you've got somebody revealing a part of themselves that I don't think they would ever do anywhere else."

Professor Green, meanwhile, is known for being a very open celebrity, but still surprised Bishop with how much detail he went into about the past.

"Everyone knows he got stabbed in the neck with a bottle. But how that affected his view of mortality, of what he should do with his life, about his own mental health and then how that fed into his understanding of his father's mental health... all of those things you don't see when you read the newspaper headline, 'He was stabbed in the neck'."

When it comes to his interview approach, down-to-earth Bishop, who got his big break after appearing on the Jonathan Ross show in 2010, thinks it's important he doesn't have, say, an earpiece in with someone telling him what to say next.

"This show is predicated on the fact that my second question is based on your answer to the first question," he explains matter-of-factly.

"I understand there's a story behind them, but I don't go in with an agenda about, 'Right, let's get to that point,' because when you want someone to talk about themselves for an hour, you will get to that point anyway, you don't have to go diving into it.

"If there's been a significant moment in their life, they'll tell you about it."

If the tables were turned, is there a subject he would really like to open up about, like McGuinness did?

"Everybody has layers..." suggests the star, who has three grown-up sons with childhood sweetheart Melanie.

"The biggest thing that's ever happened in anyone's life is your family, isn't it? They're the most important thing in your life, and they're the only thing that can elicit a reaction like that. But for me, I haven't got something where I go, 'God, I'm desperate to say this'."

Smiley Bishop is clearly proud of his series: "Now that we've done 40 hours of television in a short space of time, you know it's got legs," he quips.

And, as a football fan, (he supports Liverpool FC and even used to play semi-professionally himself for Southport FC) there are still guests he is desperate to meet on screen in the future.

"I'll be honest, the list that we put forward, every year Steven Gerrard is at the top."

But there is the odd challenge he faces as a chat show host.

"Coming up with guests when you're trying to match an audience expectation is difficult, because Steven Gerrard might be great for me, but may not be suitable for the channel," he says.

"So, that's the only limited thing. But for me, if I was doing this as the only thing I did on telly for the rest of my career, I'd be happy with it."

What about following in the footsteps of fellow funny Briton James Corden, and trying to make it in the States?

"We could go and do an American version of it, definitely. So, would I?"

He pauses. "Yeah. That should be the headline."

John Bishop: In Conversation With... returns to W channel on Thursday July 5