It is a perfect Great British Bake Off afternoon. The sun is shining on a wedding-white marquee in the gardens of a grand old country house in Berkshire and flour-dusted amateur bakers are fretting over their creations. Meanwhile the stars of a series that attracted more than 9 million viewers for its finale last year are gathering in a walled English garden for a cup of tea and a natter.

In theory the pressure should be on. For series five, Bake Off will move from BBC2 to prime time on BBC1. And yet while it may now be one of the jewels in the BBC’s crown, the Bake Off shoot is a thoroughly relaxed affair. Then again many on that team have been on the show from the start and can recall the days when it changed location every week. They should know exactly what they’re doing by now.

Meanwhile the show’s “faces” – judges Mary Berry and Paul Hollywood, plus comedy partnership Sue Perkins and Mel Giedroyc, who present – spend so much time in each other’s company a familial bond has developed. Now they sit down, alongside executive producer and Bake Off creator Anna Beattie of Love Productions, to discuss the show’s history, appeal, and the role one well-endowed squirrel has played in their success. And it soon becomes clear this is going to be a lively affair.

Prepare yourself then, for the Bake Off team in full flow and expect some of what they say here to be taken seriously and repeated as gospel by the more headline-hungry corners of the media. As Perkins almost bellows at the beginning of each round: Ready, Steady, Talk!

Where did the original idea for Bake Off come from?
Anna Beattie We just thought there was something in the village fete baking competition that hadn’t been done. But it took us a long time to convince anyone else.

How different was it?
Anna Not very different. It started as a national competition to find Britain’s best amateur baker.
Sue Perkins And now it’s an hour of innuendo presented by middle-aged women.
Anna We then spent six months in development , until we ended up right back where we started, with the original page that went to Janice Hadlow [then controller of BBC2] in early 2009 – and we’d been pitching it for four years before that.
Mel Giedroyc Did you send in some scones with the pitch?
Anna No, but I did take some to the first meeting about it.
Sue You horrid creep.

Who was first on board?
Anna We had a development team going out to find judges.
Sue They were easy to find. They were all at home. Mary was probably somewhere in Hardy’s Wessex judging some very intense Victoria sponge off. Or in Pacha nightclub ripped to the tits.

Anna Mary’s was one of the first taster tapes that we saw, it was early in the morning and I said I think we’ve got our judge.
Mel I think I suggested Mary.
Jay Rayner So you were on first?
Paul Hollywood I was on last.
Anna These things happened concurrently.

So Mel and Sue, you were approached together?
Sue We were asked at the same time. Re Paul – they really wanted one of the Fabulous Baker Boys or Dan Lepard to do it.
Paul Or Rick Stein. Any chef, basically.
Anna After we thought Mary was our judge it was just about finding the right combination.

Mel Did you actually do auditions?
Paul Yeah, yeah. I was outside, with six guys and they all looked like me.
Sue The thing is, it was only these two [Mary and Paul] who had that raw sexual animus. There was a bristling will-they-won’t-they vibe. It’s one of the great ongoing romances of the 21st century.
Anna Straight away they gelled. They got on, and had a different approach.

Why does the show work?
Mary Berry I think it works as a show because it is totally honest and I always think we encourage people to bake. We stop and explain things. I think we’re teaching in a very subtle way. We stop our bakers and ask them what they’ve done. I think it works because people look at the bakers and think, “They’re just like my next-door neighbour, or my mum could enter that… or Lizzie, she could do it”.
Mel Who’s Lizzie, Mary? Is that the Queen? She’s on first name terms with the Queen.

Did you think it would be a success?
Anna I remember Mel coming out of a voiceover and me saying to her “Honestly, it’s good.”
Mel I was the voice of doom.
Sue When you think of a baking show it’s got to be more than the sum of its parts because we’re inured to food shows and it needs to be something more than that.
Mel There was a plethora of food shows on telly, so I just thought… “Really?”
Paul The difference is there’s millions of cooking shows and no baking show.
Sue For me, the joy is you’ve got a quite conventional reality format but against that you’ve got people who don’t want to be famous, who aren’t interested in the process of television. They just want to be good bakers. There’s a really solid heart. Sometimes you go to talk to bakers at the end of a bake and they don’t put on fake smiles. They just say: “Go away, my pakora isn’t perfect.”
Paul When you’re doing a specific cooking show recipe you have to go out and buy specific things. But most people have butter, sugar, flour, eggs, yeast at home. They could bake something straight away. It’s more accessible.
Mel It’s a kind show too.
Anna We always wanted to it to be a show that a 16-year-old or a 90-year-old could enter.
Mel I love the facboys watch it.
Sue A woman said to me: “Thank you, my teen son stays at home and watches your show instead of going out on the razz”.
Paul Baking is therapy. It works.
Sue It’s about living in the moment. First you’re weighing, then you’re sieving. You don’t have time to think about things that mar your mental landscape.

When did Bake Off really take off?
Mel The squirrel in series two, with the balls [incidental footage of a squirrel caused a fuss on social media in 2011].
Sue It’s hard to say which series it was, because those balls cast a long shadow.
Jay Do you just put up with this Mary?
Paul It was Mary who filmed it.
Mary I’ve already had trouble from him this morning.
Sue Has he been naughty?
Mary I was making very normal comments about the size of somebody’s pasty.
Paul You said you like a big one.
Mary Yes, I did.
Sue She likes a big ball in her mouth.
Mary (Sighs).
Sue Mary’s the worst… she always says she likes the taste of plums in her mouth. Nobody makes her say that.

Mel It was when the squirrel went viral, and I thought “Hang on, ooh, we’re on to something.”
Paul People started approaching me on the street with baking questions in series two. They would be checking inside my shopping basket to see if I had flour in there.
Mel Then John Humphrys on the Today programme began talking about sales of weighing scales going up.

Sue There’s a very grave danger that you take it too seriously. I do a thing with the bakers called the cake telescope which is when they’re crying about something. I get them to shut their eyes, walk back a pace and then open them again just to see it really is only a cake and we really are only making a show about cakes, as much as it might be loved.
Paul Cake and other things. There’s bread too.
Sue You can become a little too self-absorbed by viewing figures. Our job is very simple. Mary and Paul do a little judging, and Mel and I make sure the bakers are all right.
Mary You help them to relax.
Mel We try and jolly them along. They can get jolly stressed.

Mary, is it slightly odd at this point in your career to have become the baking mother of the nation?
Mary It’s wonderful. I count my blessings every day. I love the whole team, because being ancient I get terribly well looked after.

What about the move to BBC1?
Mel Not a thing has changed.
Paul Except Mary demands a golden throne now.
Sue We can’t look her in the eye. She’s like Tom Cruise.
Anna The BBC’s logic is that it’s a big show and it deserves to be on BBC1, not that it needs to change to be on BBC1. They actively want the same show.
Mary We as judges have no pressure from anybody, which is wonderful. It’s our decision.

Is coming up with challenges harder now?
Mary It is tough. They’ve got to be achievable and not just fancy. We get great help from researchers and I keep a list at the back of my diary.

You get accused of coming up with very tough technical challenges.
Sue Paul loves that. He loves the idea of being the bad boy of baking.
Paul They’re not difficult. They’re attainable. But they may not have seen them before.
Jay Are there still enough challenges to set?
Paul Baking has so many different aspects. I think we’re only beginning to scratch the surface.
Mel Really?
Paul Seriously.
Mel God, I thought you’d be having trouble.
Paul We’ve been talking about going back to basics again. The bakers have got so much better. They’re almost professional before they’ve started.
Mel They watch all the series.
Sue And read all the books. There’s no innocence any more.
Mel Everyone knows everything, but they still muck up.

What’s the downside to such a successful series?

Mel There’s only a certain amount of puns you can make about buns.
Sue We started with double entendres about rings and tarts and buns and then you get to the single entendre where you are literally just going round and saying that looks like a penis.
Paul The hardest thing is when you stop and realise how much you enjoyed it because while you’re doing it, it is hard work and long hours.
Anna But there is a whole new set of bakers every year and it feels like a whole new thing.
Mary This year, and I know you’re going to agree, we’ve never had a batch of bakers at such a standard. That’s because we have so many thousands applying, more people watching, so we get the cream.
Sue Series one, Edd [Kimber]blew everyone away with a macaron and now everybody is making them in week one, just to dress a bake.

Are they using their knowledge of your tastes to attempt to get better marks?
Paul Yes. There are certain things that I like and Mary likes, which people know about and which are coming into the bakes.
Sue They might know that one likes lime and the other doesn’t like coconut.
Anna But when it gets to the judging that doesn’t necessarily help at all.
Mel Some people have been hoist by their own petard.

Do you get emotionally involved with the contestants?
Mary No. We don’t stay with them, we don’t have meals with them.
Sue You keep a critical distance, whereas we do get very involved. A lot of our role is pastoral and off camera. I have email contact with them afterwards. Why wouldn’t you? We spend the entire summer with them.
Paul I’m only interested in what’s on the plate.
Sue He doesn’t even know their names. He just knows the bake.
Jay Do you warn contestants about being in the public eye?
Anna We do, we spend a lot of time talking to them about that. It’s important. Before we even have them on the show we walk them through the likely impact, what it might be, what they might have to deal with, press attention and so on. We’re in touch with them through the transmission period too.
Sue But you can only do as good a job as possible. In the end we’re here in a tent and people are making delicious food and we’ll have a laugh. And then we’ll eat. Then we’ll go home to real life.

It’s at that point, as Sue Perkins is musing on the body image implications (or otherwise) of a job involving an awful lot of cake, that a producer appears to tell the foursome they are needed back on set. There are the results of this morning’s signature bake to announce, followed by the four-and-a-half-hour technical. And then tomorrow it’s the edible carnival that is the showstopper.

For a minute or two they get all nostalgic for last year’s showstopper high points. “John’s gingerbread Colosseum was amazing,” says Sue. “I loved James Morton’s bicycle made from Paris Brest,” says Mel. Paul agrees. “It was delicious,” he says, despite the fact that he’s famous for disliking bakes which are too much style over substance. “I’m bored of substance,” he says self-mockingly. “I just want style now.” They all laugh. They all know it’s not true. And so they head back down to the marquee. Bake Off is back.

The Great British Bake Off will be on BBC1 in August