“Leavesden is Hollywood in Hertfordshire,” says the man in charge of filmmaking at Warner Bros. Studios Leavesden.

Mission: Impossible – Rogue Nation, Paddington, Sherlock Homes, Edge of Tomorrow and not forgetting the Harry Potter series were all filmed at the Leavesden studio’s and that in itself has not only boosted the local economy, but put Watford on the map for tourists says Dan Dark, the senior vice president and managing director of Warner Bros. Studio, Leavesden.

But what makes this county such a great place to come and film?

“Hertfordshire has a very diverse range of locations,” explains Dan, “whether it is historic buildings, estates, town centres. There’s a huge variety – added to that the proximity to London is a real advantage to anybody who happens to be based in London.

“You can move from a stately home to an airport, or from the countryside to the middle of town in a very short period of time.”

Dan – a former film producer himself, adds that Warner Bros only purchased the studios in Leavesden – previously a Rolls Royce factory where they made aircraft engines – after they had completed filming the Harry Potter series.

Sitting in the building where the films were shot, he tells me: “We have subsequently invested over £150 million in completely redeveloping the studio and creating the studio tour. So in 2012 we opened the studio tour and reopened the studios as a brand new facility.

“The studio tour is the real deal,” he says about the The Making of Harry Potter. “It came directly from the film production. It is the first time that the British film industry has put on display the incredible talent that we have in the UK. When you go round the tour and you really look at the level of detail that’s gone into every set, prop and costume, it’s quite extraordinary.

“I’m really proud of what is there and I know that the film crews who worked on the films are hugely proud of having what they created out there on display.

“We kept absolutely everything throughout all of the films,” says Dan. “With Harry Potter it was quite an unusual situation, it was eight films, filmed over 10 years and when they started filming all the books hadn’t come out yet. So no-one knew what we may or may not need. Now we have an entire team of archives who are responsible for looking after all of the assets.”

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He vaguely adds that there may be “lots of things to look forward to” with the Harry Potter studio tour, and that it is always “exciting to refresh it”.

And it’s not just the Harry Potter tour; speaking about the investment the film giant has made to the local economy, Dan who sits on various community and educational boards including Watford Business Leaders and Hertfordshire Local Enterprise Partnership, explains that Three Rivers District Council recently approved a master plan, which will see the studio expand to facilitate more workshops and stages.

“This will continue to directly benefit local businesses including hotels, suppliers, restaurants and taxi companies.

“We have the latest facility and this is why Hollywood directors, producers and filmmakers want to come here. It is the new Hollywood.”

Dan is the only one who has seen Leavesden studios evolve from factory shells to the high-end facilities. “I came in 1994, – when producers needed somewhere to film the James Bond Golden Eye movie and there was no studio space available in the UK at the time so they took the decision to find a temporary facility to use as a studio for the one film.

“I converted the old aircraft factory into a temporary studio facility and I have been here ever since.”

Dan, who himself has worked on five James Bond films, two Pink Panther films and three of the Alien films, says: “It’s funny when people come back who have worked on Harry Potter the first thing they say is where are the leaky roofs. I am the only person to still be here and I have never left my office.

“I came into this room back in 1994 – it was the old control tower – and it was really dingy, lots of little rooms and you could see the radar room and there were switches, it was dull, paint peeling off the walls, but I just had this vision of this great office, with the rounded environment.

“I like to be very inclusive so I don’t like square tables as then you end up with someone at the head of the table. So this office is very much a part of me and I have fought very hard to keep it,” he laughs. “It’s been refurbished though.”

This year marks the 15th anniversary of Harry Potter and the Philosopher’s Stone and to celebrate, Warner Bros. Studio Tour have been holding limited exhibitions throughout the year. Coming up, for the first time, Privet Drive opens its doors to the Dursley’s home.

Visitors can see not only how the interior looked, but Harry’s Hogwart’s letters will be suspended in the air as though they have just flown through the fireplace.

The Making of Harry Potter Studio Tours, Leavesden, May 27-June 6. wbstudiotour.co.uk.