Remains of the school day: David Walliams and Catherine Tate in Big School

When David Walliams saw the film version of Kazuo Ishiguro’s novel, he thought: there’s a comedy in this. But why set it in the classroom? James Rampton finds out

One hundred and thirty-two pupils at the fictional Greybridge School have crowded into the school hall and are screaming with excitement. They are in the middle of watching a major set-piece scene from David Walliams’s new sitcom, Big School.

The pupils are shrieking with delight at seeing a group of well-known actors dressed as their schoolteachers making complete fools of themselves (all in the cause of art, you understand). The teachers are unleashing their inner divas at the school talent show, “Greybridge Has Got Talent.”

Walliams and Catherine Tate, who play the deputy head of chemistry Mr Church and the new French teacher Miss Postern respectively, are collaborating on a version of “Imagine” that may well have John Lennon revolving at high speed in his grave.

Meanwhile, Philip Glenister, who plays the not-as-macho-as-he-thinks PE teacher Mr Gunn, is dressed in a laughable outfit comprising a horrid bouffant blond wig and matching handlebar ’tache, a hideous turquoise jacket with the sleeves rolled up, and a horrendous Hawaiian shirt open to the navel and revealing a glinting gold medallion underneath. Yes, you’ve guessed it, his “talent” is impersonating kitsch comedian Keith Lemon.

Furious that his act has been beaten by Mr Church and Miss Postern’s rendition of “Imagine”, Mr Gunn mutters bitterly to a colleague: “No, no, no. This is a fix. In what universe does it say that John Lennon is better than Keith Lemon?”

Big School, which begins on BBC1 at 9pm on Friday, owes its inspiration to an unlikely source: a Merchant Ivory film. Like the two principal characters in The Remains of the Day, Mr Church and Miss Postern harbour a deep-felt love for each other, but are too awkward and English to express it. All the while, the oafish Mr Gunn tries to muscle in on their relationship.

The other problem for the would-be lovers is that Mr Church, who tells people that he is married “only to chemistry”, is hopeless with women and has to resort to taking romantic advice from a streetwise boy in detention.

In this likable sitcom co-written by Walliams (who has carved out a successful second career as a judge alongside Simon Cowell on Britain’s Got Talent) and The Dawson Brothers (who wrote for BBC1’s The One Ronnie), the teachers are universally shambolic. Even the head, Ms Baron (Frances de la Tour), sets a terrible example, spending all her time downing the booze she has confiscated from the pupils. Clearly, Greybridge is a school where the teachers are far more childish than the pupils.

In a break between scenes at the real-life Bishopshalt School in Hillingdon, west London, the three leads are relaxing in the textile room – as you do. Surrounded by reproductions of Gaugin and Hockney and a poster reading, “Keep calm and sew on”, 45-year-old Tate jokes that she only took the role of Miss Postern because she thought Walliams might help her to meet Cowell (who – spoiler alert – sadly does not make a special-guest-star appearance at “Greybridge Has Got Talent.”)

The actress, who has also starred in Doctor Who, the American version of The Office and her own BBC2 vehicle, The Catherine Tate Show, proceeds to consider why the two teachers are attracted to each other in the first place. “They are drawn to each other without realising it. They have a connection because they’re both square pegs in round holes. But they’re not aware of the attraction until further down the line.”

Forty-one-year-old Walliams explains that Big School was inspired by one of his favourite movies. “The Remains of the Day is one of the best films I’ve ever seen, but there is still something inherently funny about the fact that the two main characters [memorably played in the film by Anthony Hopkins and Emma Thompson] can never express their feelings for each other.”

“So I came up with the idea of writing a sitcom about two teachers who meet and fall in love, but they’re too shy to make it happen. It is essential that they never express their emotions. Most romantic comedies are over the moment the main characters get together. Look at Bringing Up Baby. It’s vital that there is continuing tension in this comedy. So this is The Remains of the Day meets Grange Hill.”

Walliams goes on to reveal that the original title of the series was Autumn Leaves, after the Nat King Cole song. He remarks that, “It’s a very romantic song, but it’s also about people in the autumn of their lives. When you’re past 40, your approach to romance is different because you’re not young anymore. I thought that was a good comic idea to play off.”

Like many of the best sitcom characters, the teachers in Big School are all terminally self-deluded. For instance, Tate observes, “Miss Postern is a French teacher who’s never actually been to France. You might think that’s a slight disadvantage, but she doesn’t see it that way. She does not have an awful lot of self-awareness.” Tate herself speaks fluent French, “So I’m having to bring my own French down a notch, just to make it believable!”

Mr Gunn is similarly blind to his own deficiencies. Glenister, 50, who is best known as the delightfully dinosaur copper Gene Hunt in Life on Mars and Ashes to Ashes, comments that, “Mr Gunn is a PE teacher who is horribly unfit. He’s slightly grotesque, and there is a sadness about him because he still lives at home with his mum. He and Mr Church start competing for Miss Postern’s affections. Mr Gunn thinks he can date everything that moves. He reckons he is a real Lothario, but in fact he is all mouth and no tracksuit bottoms.”

The actor says he has particularly enjoyed playing a PE teacher as he was pretty sporty himself at school. “I was in the school football team. We had this wonderful teacher who decided that the football team should start learning Scottish country dancing. She had this theory that footballers would make great dancers. Sadly, halfway through the first lesson, she was proved completely wrong.”

Over the years, school has proved a fertile setting for British sitcoms, ranging from Please Sir! in the 1960s to more recent offerings such as The Inbetweeners and Bad Education. Walliams reflects on why school works as a backdrop to comedy. “School is a universal experience. There is also an element of performance from teachers in front of kids.

“And for Miss Postern and Mr Church, there is so much that can go wrong. It’s a love story, but they can never have any privacy. In the corridor or the staff room, they can never have a one-to-one conversation.”

Appearing in this sitcom has prompted memories among the cast of how school helped them acquire a taste for performance. Tate recalls the thrill of first discovering that she could make the class laugh. “I didn’t stand in front of them doing a stand-up routine using a pencil as a microphone. But I learned that if you stay the right side of cheeky, chatting back to teachers is a good way of getting people onside.”

‘Big School’ starts on Friday at 9pm on BBC1