Backstage during filming of the ITV quiz show The Chase, it's giddying just thinking about the combined brainpower.

It's a rare event to have all five of the Chasers – the quiz experts whose job it is to stop contestants walking away with too much money – in the same building, but today we've managed it for a special photoshoot to mark the tenth anniversary of the hit show.

Host Bradley Walsh, who jokes that he's the least clever member of the line-up, is here too, talking about how there's barely a question you can throw at them that these guys can't answer individually.

Their combined intellect could power us all to the Moon, surely? Well, a hilarious encounter in Anne Hegerty's dressing room puts paid to that notion.

The quizzers and host of The Chase (pictured from left: Paul Sinha, Jenny Ryan, Bradley Walsh, Mark Labbett, Shaun Wallace and Anne Hegerty) discuss the success of the show as it celebrates its tenth anniversary

Anne, known as The Governess on the show because of her take-no-prisoners approach, likes to keep track of filming via a live feed from the studio.

Today, though, there are technical issues, she says, and an engineer has been summoned.

He arrives, and as she explains that no matter how many buttons she presses the monitor will not work, he goes to investigate.

It takes all of one minute for him to lift the TV plug and insert it into the wall. Ah.

'Well that was embarrassing,' she says, seeing the funny side.

'I must admit I didn't check that the thing was plugged in. You see, I'm only clever about certain things.'

In the fickle world of the TV quiz show, it's always hard to predict which formats will take off.

The fact that they've just finished filming the tenth anniversary episodes tells its own story about the juggernaut The Chase has become.

The show sees four strangers work as a team to answer general knowledge questions to build up a pot of prize money.

They then must go head-to-head – individually and as a team, with one of The Chasers.

Three episodes of The Chase are filmed each day; the relentless pace is scheduled around Bradley's (pictured left with a contestant) acting schedule

If they can outpace The Chaser in terms of correct answers, they get to keep the prize money at the end.

The show is filmed in chunks – three episodes a day – and the pace is relentless, because all the filming must be done around Bradley's acting job on Doctor Who.

The word on set is that Bradley, 59, is quite the workaholic.

'I worry about him having a heart attack,' says Anne. Bradley is not impressed.

'I think Anne should take a look in the mirror,' he retorts.

Still, it's a fine display of the banter that characterises the show.

It's bonkers that I'm being paid to quiz - Anne Hegerty

The Chase's big rival is the BBC's Pointless, which airs at the same time, 5pm – the teatime slot ('No one with a job watches us,' admits Anne, 60).

But The Chase gets a staggering 40 per cent of the audience tuning in at that time, around 3.5 million viewers an episode.

Interestingly, the shows are neighbours, filmed in the same studios, with the stars' dressing rooms back-to-back.

Pointless host Richard Osman is an old colleague of Bradley's, and Bradley says he likes to wander onto the Pointless set when he's not busy.

That must cause the studio audience no end of confusion.

Bradley (pictured with Anne), who wasn't a natural choice to front The Chase, believes the show has a different audience to their BBC rival Pointless

'Absolutely, but it's great fun,' he says. 'We go back a long way.'

Awkward, though, given that the two shows are battling for the same audience.

'Well, the BBC aren't all about ratings,' says Bradley.

Actually, they have very different audiences, he says.

'Theirs is quite a gentle show. Ours is more in-your-face, quicker paced, a bit more crash-bang-wallop.'

Bradley wasn't the natural choice to front the show when it started.

Although he had quiz show experience (from hosting Wheel Of Fortune), he was more famous for his work in Coronation Street and Law & Order: UK. But his deft handling of the quiz show role – big on jibes and cheekiness – has been credited with much of the show's success.

'Obviously I'm biased,' says Mark Labbett, 53, the man-mountain of a Chaser known as The Beast.

'But I think he's the best quiz show host in the world.'

Mark has a theory on why the show has all TV executives watching its success.

Anne (pictured) was the Chaser at the time of the show's biggest win; a team took home £100,000 in 2018

'I heard that while it's not ITV's highest earning show, it is its most profitable.

'Game shows are relatively cheap to make.

'Richard Osman has talked about how Pointless can get the same viewing figures as The X Factor for one-hundredth of the budget.'

Mark does take issue with some of the daytime BBC prize jackpots though.

'On some shows the prize is a couple of hundred quid. Come on! You can afford more than that.'

The biggest win on The Chase was the £100,000, taken home by a team in 2018.

Anne was the losing Chaser on that one.

And it's the fact that the Chasers are fallible that makes the show such compelling viewing. They are all notoriously competitive.

So who is the worst loser? 'Mark, by far,' says Anne.

'He hates losing and thumps the set and walks off. But he's the fastest. I'm the slowest, but I'm quite accurate.

Chaser Shaun Wallace (pictured) has continued his career as a barrister despite the success of the show, and says it isn't difficult to juggle the two professions

'Paul Sinha [The Sinnerman] scores the best in national and international quizzes. Jenny [Ryan, aka The Vixen] is great on pop culture.

'And Shaun [Wallace; The Dark Destroyer] is the best in the world at football quizzes. He's also the nicest of us all.'

Until The Chase came along, being a 'professional quizzer' (that's how the five describe themselves) wasn't possible.

Some could make a living by setting questions for TV shows, but it wasn't a front-of-house job.

The Chase changed all that. In the early days all the Chasers had day jobs.

One still does. Shaun, 59, is a barrister, and has been in court today working on a murder trial before our photoshoot.

'It's not difficult to juggle the two,' he says. 'They are so different.'

Paul Sinha, 49, was a doctor before making a shift into stand-up comedy. But quizzing was his hobby, his passion.

'I'd never considered making a career of it, but it turned out that it was possible,' he admits.

Jenny Ryan, 37, (pictured second from right) set questions for the early series, before joining in a full-time capacity as a Chaser

Bloopers that set The Chase apart TV quizzes can be a bit po-faced, but Bradley says it's the laugh-out-loud aspect of The Chase that gives it the edge. His crack-ups over innuendo-laden questions are legendary. Bradley (pictured) revealed one of his favourite innuendo-laden questions of the show was the infamous Fanny Chmelar one His favourites over the years? A classic was the 2012 question about what the Andy Capp character is known as in Germany. Is it Dick Tingeler, Helmut Schmacker or Willi Wakker? Bradley couldn't even say the name Dick Tingeler without convulsing. It has now become a YouTube classic. Then there's Fanny Chmelar. The question of which sport this athlete competed in was a straightforward one in 2011 (she's an alpine skier), but saying the name out loud was just too much for Bradley. There are many moments where the entire studio collapses into giggles, and these have been turned into The Chase 'blooper' shows. The aim is to get the audience laughing, he says. 'We are an entertainment show first, then a quiz show.' There are also the unforgettable (if rare) moments when the Chasers drop a clanger. The favourite here is still Paul Sinha's epic fail when he was asked what tennis player Andy Murray tied to his shoelace in 2015. The possible answers were – his front door key, his wedding ring, or a piece of haggis? The correct answer was, of course, his wedding ring. Sinha will never live down his choice – a piece of haggis. Advertisement

Anne had a variety of jobs, working as a journalist, then in publishing, before she was recommended to the production team by Mark.

Jenny Ryan, at 37 the baby of the team, studied law at university and actually set questions for the early series, before joining in a full-time capacity.

And in his previous life, Mark was a supply teacher. Does he think the skills are transferable? Absolutely, he says.

'I basically treat the contestants as if they are a Year 11 class on a wet Wednesday.'

Paul's not the only one who's astonished that he can put 'quizzer' in the profession box on official forms.

'It's bonkers that I'm being paid to quiz,' says Anne.

'When I said to my brother that my job was a professional quizzer, he snorted his drink out of his nose.'

All the Chasers were the sorts of kids who loved games and quizzes.

Anne (pictured centre) who was in her 40s when she realised that she has Asperger's Syndrome, revealed she was struggling to pay her mortgage before joining The Chase

Jenny's whole family were competitive, to the point that 'one of us actually got injured playing a card game'.

The mind boggles. Mark was a young maths whizz, possessed of a near-photographic memory too.

'It's not quite photographic, but I could look at places on a map once, then recall them without any trouble at all.'

Anne realises now that she was displaying symptoms of Asperger's Syndrome when she was a child, including being obsessive about certain subjects.

She only realised she had the condition when she was in her 40s – and then everything made sense.

'Things like having tantrummy meltdowns, over things that shouldn't trouble you past the age of three, I suddenly realised why.'

She admits that 12 years ago she was struggling to pay her mortgage and that joining the show 'was like winning the lottery'.

They all sound grateful that The Chase found them.

'There are quizzers who are much better, but for The Chase they were after big personalities,' says Mark.

Mark (pictured) was given a quizzer role as soon as his 6ft 7in frame came through the door for the audition

'The two don't always go hand in hand.'

Mark was told he had the job in the bag as soon as his 6ft 7in frame came through the door for the audition.

'I was wearing an Army greatcoat, and the coat tails swung like Superman's cape,' he laughs. 'I was told that was it.'

Bradley gave them all their all-important nicknames.

'It's something I've always done, I did it on Coronation Street. Here it was easy.

'When I met Shaun – they call us 'the twins' because we were born two days apart – he told me he was a boxer and a good friend of mine, Nigel Benn, was known as The Dark Destroyer.

'Shaun loved it.'

Jenny points out that there's a touch of 'panto villain' about them all.

'She's a character,' she says of her on-screen The Vixen persona.

Paul (pictured) who has recently been diagnosed with Parkinson's Disease, says he feels prepared for new challenges now that a treatment plan is in place

'She's more confident than I am. Mark put it best when, on my first day, he told me to be myself – but with the volume turned up.

'The Vixen is meaner, cockier, more outgoing than I am.'

Anne says her character is partly based on her grandmother, who was 'a bossy old cow', and the Dowager Countess of Grantham.

'I always seem to be playing somebody played by Maggie Smith.'

Except Maggie Smith would struggle to carry off the austere costumes Anne wears. And the scaffolding underneath them.

Her bra has its own hanger in her dressing room, and could double as a hammock.

The Vixen is more confident than me, she's meaner, cockier - Jenny Ryan

'Bras have featured heavily in my life. Heavy engineering, guys,' she laughs.

Paul is the quietest of them, but there's a reason for him being a little more downbeat.

It emerges after our day on set that he has just been diagnosed with Parkinson's Disease, which affects the brain.

It's a terrifying diagnosis but he's astonishingly upbeat about it.

'With the diagnosis now confirmed, and a treatment plan in place, I feel far more prepared for the new challenges ahead,' he said in a message to fans on his website.

Jenny (pictured) says her Vixen persona on the show is a meaner, cockier and more outgoing person than who she is in reality

'I fully intend to keep Chasing, keep writing and performing comedy, keep quizzing and keep being hopeless at things.

'Dancing On Ice is, I suspect, out of the question!'

Obviously, all this does call into question how the show will develop.

Mark reveals that he's helping train up a new generation of Chasers, 'because it's not easy to get someone who can just step into the job'.

He hopes the show has the staying power to still be around in another ten years, and he even has a pipe-dream that his own son – just one year old – could one day step into his shoes.

'Maybe he will be smart enough to step into the job as Mini Beast,' he suggests.

What of ringmaster Bradley? He – perhaps sensibly – seems bemused at the idea that anyone should look that far ahead.

'Who knows whether it's got ten weeks, ten months or ten years? But long may it reign.'

The Chase, weekdays, 5pm, ITV. The Celebrity Chase will return later this year.