WALKING down the red carpet for a film premiere in London’s Leicester Square is an experience no one would probably never forget.

But it must have surely been even more special for Rose Hill comedy writer Richard O Smith to do it for the 3D animated film he wrote the script for.

Mr O Smith, who lives with his wife Catherine in Rivermead Road, has for the last year been writing the English version of the Argentinian animated film The Unbeatables, which hit UK cinemas on Thursday.

The film, produced by Victor Glynn of Walton Well Road, north Oxford, follows Amadeo, a young boy and master table football player, who is challenged to a grudge match by his childhood bully, with the fate of their home town hanging in the balance. Mr O Smith, 50, got to work with film stars Rupert Grint, Ralf Little, Rob Brydon and Antony Head in a London Soho studio where they recorded their voice parts.

He told the Oxford Mail: “There was a lot of pressure, mainly because we were making a movie in a way that has probably never been done before. Effectively, the movie had been shot and finished and I was then having to write a script to it.”

The Argentinian version, dreamt up by Oscar-winning director Juan José Campanella, proved to be a huge success, outgrossing Despicable Me 2 and Monsters University.

But when producers decided to create the English version, they first had to have the Argentine-Spanish version translated, Mr O Smith said. It was then his job to “make it funny”.

He added: “And it was not just in Argentinian Spanish, it was – by the director’s own admission – in Argentinian Cockney Spanish.

“I only expected to get the job for a couple of weeks, but there were all sorts of direction changes and I ended up working very closely with Juan José Campanella on it because he had very clear ideas of who the characters were.

“But writing the jokes was almost madness, because I had no control over timing.

“It was very difficult getting them all to fit in with the lip syncing of the characters. But the animation looks glorious, and it has been independently funded to the tune of $23m.

“We did change some of the characters too, in particular we felt female characters were underepresented, and gave Lara (Eve Ponsonby) a more prominent role. I’m also proud of the ending, which is brave. You would never get away with it in a Hollywood production.