"I've seen unbelievable things. The dazzling antimatter fountains of Caiclos; gravity beams blazing from the dying Eta CarinaeA star system in the constellation Carina. It is more than five million times brighter than the Sun.; beings with their bums where their mouths should be. But I've never had more fun than that day in a place called TootingA district in South London with large Indian and Pakistani communities. Its high street is built on what was once a Roman road running from London to Chichester. In Norman times it was owned by the De Gravenel family and known as Tooting Graveney. on a planet called Earth. That was where I met the strangest life form I've ever met in any dimension - teenagers."

Spoken over dramatic footage of our planet seen from space, these are the opening lines of 7 Hours On Earth, a hilarious and inventive film whose plot is borrowed from Shakespeare's A Midsummer Night's Dream.

What makes it remarkable is that it has been made by the community of Graveney School in south London - teachers, pupils, ex-students, parents and even family pets.

In Shakespeare's play, young lovers have their relationships manipulated by fairies, with unforeseen and very funny consequences. But this film transposesMoves. In music, transposing means performing a piece in a key different from the one it was written in. the action from a wood near Athens to Tooting.

It has the humans' lives directed by aliens, who crash land in the headmaster's study and take over the nearest life forms - the headmaster, deputy head and several pupils who are in the middle of a major telling-off.

What puzzles the aliens most, apart from the unfamiliar human bodies, is teenage love in all its complexity. They use their superpowers to create an app that they hope will make everyone happier in their relationships - but it only makes things worse.

The film is the brainchild of Patricia Sharpe, who teaches English and film studies at Graveney. "I would spot then vivacityLiveliness. A person with lots of energy is sometimes described as "vivacious". and liveliness of the students, and wish I could put them in a film," she says. "It felt like a vast talent pool." It proved, however, to be a long process: 7 Hours on Earth was shot in 2017, but - with all the editing and promotion involved - has taken three years to reach the screen.

Determined that the movie should be as professional as possible, Sharpe called on teachers' friends and relations with film experience to train the students. The technical crew consisted mainly of media students from year 10 upwards; the special effects were designed by ex-pupil Ollie Hall, who was in his first year at Dundee University.

"It was a big learning curve," he says. "One of my favourite things was when one character transforms into a ball of light and begins to shimmer. I was pretty proud of that."

The cast includes Ramona Marquez, who was then in the sixth form and has gone on to find fame as Karen in Outnumbered. A last-minute recruit, Karl Queensborough, is now known as one of the leads in the musical Hamilton. Money was raised by crowdfunding, with one donor paying 100 to have their pet greyhound appear in close-up.

Inevitably, there were hitches in filming, such as the day some crucial props got lost. "I phoned Ismat, my assistant, who was on the bus in Tooting," Sharpe remembers. "I said: 'Are you anywhere near Primark? Get off, go in - we need 10 earrings that look like alien transmitters!'"

Some say, yes: we are capable of much more than many of us realise. The singer and actress Marketa Irglova was almost unknown before she appeared in the independent film OnceMade for the tiny (in cinema terms) sum of 100,000, Once is the story of two struggling musicians set in Dublin., but won an Oscar for the song Falling Slowly. It was, she said in her acceptance speech, "proof that no matter how far out your dreams are, it's possible. Fair play to those who dream and don't give up."

Others argue that we should be careful what we dream about. Many people imagine themselves scoring the winning goal in a World Cup final, but unless you are brilliant at football, there is no chance that it will happen. Even if you have talent and work hard, you still need luck, which may not come your way. It is good to aim high but useful to realise you will not get everything you want.