More than 10 years ago, Norfolk-born set designer Stuart Craig was asked to work his Oscar-winning magic on the first Harry Potter film.

Since then his life has been taken over by Quidditch World Cups, defence against the dark arts lessons, and an epic battle to defeat the evil Lord Voldemort.

But as the final instalment of the JK Rowling epic wows audiences at cinemas for the last time, the former Norwich Art School pupil and his Norfolk set decorator Stephenie McMillan say they have not yet left the wizarding world.

When production designer Mr Craig and Ms McMillan were first approached to help put JK Rowling's magical world on to the big screen, they were only asked to work on the one film.

Only two books had been written at the time and neither could have anticipated the phenomenon the series would become.

But one film became two and then three and the colleagues found themselves working on eight consecutive Harry Potter films together.

'Directors have changed, camera men have changed, but there's been this core group that couldn't be shifted,' said Mr Craig, speaking at a special screening of the final Harry Potter film in Norwich this week. 'I did say 'you don't have to have us', but I think they were intimidated by our permanence.'

Sitting in the courtyard at Cinema City, Ms McMillan, who lives in Weston Longville, near Norwich, added: 'The more it went on the less able we would have been to relinquish it and walk away. It was Stuart's creation.'

Ever since filming ended on the Deathly Hallows Part 2 last summer, stories of the tears shed at the glitzy premieres have summed up the feelings of millions of fans who see the series finale as the end of an era.

But for the designer and decorator – as well as many other members of the crew – the adventure has carried on.

Mr Craig, 69, who was brought up in Norwich and still owns a holiday home on the north Norfolk coast, said: 'We've both been involved in spin-off projects.'

An exhibition at the Warner Bros studios has seen a number of the breathtaking sets designed by Mr Craig rebuilt in Leavesden, Watford, and filled with Ms McMillan's magical props.

It has been yet another challenge for the pair.

He said: 'I've been involved in the consultation on the content and choosing the sets. They are not all being built in exactly the same way as they were in the films – we've got to be able to get 5,000 people through there every day.'

The former Norwich School of Art – now the Norwich University College of the Arts – pupil was also responsible for designing The Wizarding World of Harry Potter theme park at Universal Studios in Orlando.

There is now talk of creating an extension which Mr Craig, an OBE, will also be involved with.

Even when the pair did manage to find time to work on a different film away from the Harry Potter series – Colin Firth and Cameron Diaz's new movie Gambit which is due to be released in 2012 – there was still one major reminder of Hogwarts.

'Even then we didn't quite get away from Harry Potter,' said Ms McMillan. 'Alan Rickman [Professor Snape in all eight films] played one of the lead parts.'

Mr Craig and Ms McMillan, who have worked together on a total of 17 films over 20 years, were special guests at a screening of Harry Potter and the Deathly Hallows Part 2 at Cinema City this week.

The event had been organised by the Norwich University College of the Arts (Nuca) where production designer Mr Craig studied about 50 years ago.

'My mother was extremely worried when I said I wanted to go to Norwich Art School. It had a very different reputation then,' he said.

The fine art student soon discovered a love of theatre and painted sets at the Maddermarket Theatre before finding his way to London and into films.

He has won three Oscars for his work on Ghandi, Dangerous Liaisons, and The English Patient.

victoria.leggett@archant.co.uk