Everyone thinks they can write a musical. Sometimes I get the impression that everyone has. In the course of a varied life I meet lots of interesting people, and after a while the dreaded confession emerges. I have heard “By the way, I’ve written this musical” from everyone from the stunt arranger for the James Bond films to the Minister of State for Northern Ireland. When we held a competition at the Buxton Opera House to find new musicals, we got 491 entries. These are not people who would write plays, or operas, or films. Why do they think that music theatre is somehow the easy option?

Well, one of the great spurs for artistic endeavour is the amount of rubbish about. Consumers pay good money, sit through the rubbish and cry “I could do better than that!” The other reason is that the musical exists in fairyland - a world of self-delusion, crazed smiles and happy endings “Somewhere Over the Rainbow” (lyrics by E Y “Yip” Harburg). And this fairyland is created by the great ineluctable truth that People In Real Life Burst Into Song. If it’s a nice day, people mutter “nice day” to each other. They don’t grab a chair, sit on it the wrong way round and sing “Oh what a beautiful morning!” (lyrics by Oscar Hammerstein II.).

Incidentally, why do people on stage sit on chairs the wrong way round? Have you ever seen anyone in real life, apart from Christine Keeler, sit on a chair facing backwards?

But we are not in real life. We are in the theatre. We are moved, we’re involved, we laugh and cry because there is music. But because there is music, we don’t believe a word of it. The suspension of disbelief is more volatile in music theatre than in any other form, and this suspension seems to survive the writing, the rehearsals and the previews. It is only on opening night that you find out whether the ugly duckling has turned into a swan or a turkey.

The making of a guaranteed swan is an uncertain and hysterical business. If you’ll all just stop singing for a moment and come down to Earth, I shall tell you how it’s done.

First you study. Then you study some more. You get the CD and the score of Cosi Fan Tutte, La Traviata, Carmen and La Boheme, and you listen to them over and over again, because this is where great musicals came from. Composers steeped in European musical traditions went to America and brought with them a huge carpetbag of music drama.

In America they found a frontier spirit and an eponymous dream, and they altered the music to suit. The other thing they found was a common language. English has 20 ways of saying the same thing; and that is precisely what lyric writers need, and what the Harts, Gershwins, Harburgs and Hammersteins latched on to.

Having studied the roots, we now want to branch out. We are not trying to write Wagnerian tree-trunks. We want to write the twigs and blossom. So we had better clear up the differences between opera and musical.

In opera, the music tells the emotional story, and the words are subsidiary. In musicals the words and music have equal weight. Musicals are by Lerner and Loewe, Rodgers and Hammerstein. Operas are by Puccini, not Puccini, Giacosa and Illica.

Operas make demands on singers such that they have to be performed in repertory, not on consecutive nights. This is ludicrously expensive because you’re always building and striking sets. Musicals have to be on every night, so have to be singable every night.

Opera works on an assumption of subsidy. Musicals are intended to make money. So thousands of people must want to pay to see them.

When writing a musical, we try to take the European music drama tradition and use its advantages - emotional passion, gaiety, ensemble, glamour, the ability to soliloquise without embarrassment - and make it acceptable to a wider audience by doing it in a langue they can understand. We also make that language audible by using subtle amplification and less bombastic orchestration.

We now add the twigs and blossom to our operatic trees. We are going to listen to Guys and Dolls, Kiss Me Kate and Carousel.

They are all perfect. Not a weak line, not a second-rate song anywhere. Every second verse is as good as verse one. These are shows which have been slaved over, harried and worried until they are entirely free of moments when the audience can sit back, relax and say “This is ridiculous”. And this brings us, at last, to rule one.

Hit musicals are not written. they are re-written.

Very often they start off as re-writes. All the shows I’ve mentioned - operas and musicals - are adaptations. If the audience already know the story it makes life easier. In any case, that story has to pass one or two crucial tests. Here are three more rules:- The journey in the story must be from A-Z, not just A-B. Music is wasted - and risible - on little niggles. You must make a drama out of a crisis.

There must be a “life-force” character, and a pliable foil who is changed. These characters, in any interesting story, will have elements of each other.

The life-force character will have a song about changing things, and the foil will have a song about being changed.

These three rules are not mine. They are the result of a study by an American academic, in which he analysed every musical that had run on Broadway for more than six months, and found them all to contain those elements. Ignore them at your peril.

They emphasise, yet again, that the three most important things in a musical are the book, the book and the book. Without a story, characters and emotions that demand music, we are doomed.

Let us apply these rules. We could test them on a few existing stories and adapt one that passes all the tests. I would humbly submit, for instance, that Pride and Prejudice has all the ingredients, whereas Sense and Sensibility doesn’t - it’s the size of the brush-strokes.

But Pride and Prejudice is a long novel, and singing takes longer than speech. Pride and Prejudice is also pretty much unimprovable, so making it into a musical may make it coarser and worse, not finer and better. We want a short novel with a great story, which isn’t actually very good. And I have to say I wasn’t aiming to get here, but I have inevitably reached The Phantom of the Opera, by Gaston Leroux, as the perfect subject for musical adaptation.

The Phantom of the Opera’s been done, Pride and Prejudice is too long and too good, what should we do? We will make up a story.

Later this year Richard Noble (a life-force character if ever there was one) will place a young pilot called Andy Green into a jet-powered car and encourage him to drive at more than the speed of sound. No one has done this before. Richard Noble holds the world land speed record, and is masterminding someone else’s attempt to take it away from him. I think this is a gutsy, exciting story. Let us now dress it up for the evening.

We have a huge journey - the record run - 30 seconds long, but enormous in its scale and its aims. We have the life-force character who organises the project, and the young driver whose life is changed by it.

I’m afraid I’m going to invent two entirely fictional characters as well - the young driver’s girlfriend who worries what it will do to him, and the old record-holder’s beautiful wife; you’re ahead of me - the young driver and the beautiful wife fall hopelessly in love with each other, and their love threatens to destroy the whole project.

The writers have ambition and love and jealously and fear to play with. They write some songs - “It’s going too fast, it’s out of control”, which is a duet between the wife (about love) and the driver (about the car), and they talk to the producer. (It’s the producer who changes the title from “Driven by