It might yet become one of the biggest domestic hits of the British movie year, but Attack The Block owes its earliest origins to director Joe Cornish getting mugged.

“It was quite a pathetic mugging,” the debutant filmmaker, former Bournemouth Film School student and sometime radio presenter explains.

“They were quite young kids, and the experience made me think. It made me want to talk to the kid who had done it because it seemed like a very unreal situation, it seemed like a ritual, like a sort of pantomime, but it was very scary.”

Cornish channelled the scariness of this encounter into a science fiction plot that sees an alien invasion centred on a south London housing estate.

There the disillusioned and dispossessed kids who rule the place with guile and threats of violence take up arms against this mysterious extra terrestrial foe.

“I started thinking about the movies that I loved when I was growing up,” the 42-year-old director adds. “The kind of American creature features and gang movies from ET to Critters and Gremlins, to The Warriors and Streets of Fire and Rumblefish.”

The irony for Cornish is that while he is as much at home in this urban setting as anyone, having grown up in the area, he is distanced from the street-smart characters his film depicts by the relative privilege of his own childhood.

“I’m less street than Prince Charles,” he laughs, “so I had to do some research, to make sure I was knowledgeable and as truthful as I could be about that world. Even though I grew up in Stockwell and Brixton I was ferried off to posh schools every day.

“So once I’d put together the basic outline of the story we went to loads of youth clubs around south London and talked to hundreds of different groups of kids about the story.

“Then I would write a draft and go back, and return and focus on particular areas. Lots and lots of people would draw out tiny little bits and then I’d put my own imagination on it. Towards the end of the process, when we’d cast the main characters, we involved the actors and went through every single line of the script with them.”

Once that was all done Cornish finally achieved a childhood ambition of directing a movie. So many people involved in it were first timers that it might have proved problematic, but leading lady Jodie Whittaker – a relative veteran since making her debut in Venus five years ago – recalls that the energy of the young cast proved infectious.

“It was tough because the first five weeks were night shoots,” the Yorkshire born actress says. “But the guys were brilliant, just amazing. At four o’clock in the morning I’d be tired and ratty, but they didn’t flag at all.

“In a strange way night shoots helped because you stay in your little bubble, you can’t actually do anything domestic because you’re in such a weird time frame that you just think of filming the whole time.”

“Doing night shoots is a bit like being a vampire really,” nods John Boyega, who shines as the group’s de facto leader Moses. “You’re just working at night and sleeping in the morning.”

“I loved it,” beams Cornish who in some ways seems like the biggest kid of all in this group. “For me it felt like after school fun. You’d get off school at 3.30 or 4 and then you’d do your homework and life would kick in at about five. And our shoot kicked in at about five. But it was very important to me because I’ve seen a lot of British council estate movies and I wanted to make mine look different.”

The result is a movie that wears its influences openly, and yet is true to itself and its distinctly British, urban setting. Attack The Block has already drawn praise from the South By Southwest festival, winning an audience award there.

And who knows what else will follow, with a bright and articulate director enthused by the process and a young cast who might well be destined for bigger, better things? The sign of a happy shoot is how well everyone gets on at the end of it, and how keen they are to sell the film further. This seems a very happy shoot.

“I was walking past a market stall the other day,” smiles Jodie Whittaker, “and the guy there was talking about this film Attack The Block which he said was supposed to be really good. I said ‘I’m in that, I’m the girl on the poster!’ – it’s so exciting to be a part of this. It’s brilliant.”