Deep in the heart of a Bradford archive lies Hughie Green’s old Clap-o-meter.

Other treasures stored there include James Bond-style miniature cameras, a silent movie projector and the oldest known photographic negative.

I discovered all this and more on an Insight tour, taking me on a voyage of discovery behind the scenes of the National Media Museum.

Insight is the museum’s Collections and Research Centre where thousands of items are stored. There are two libraries, housing 1,000 books and magazines, and a suite of storage rooms, each with its own micro-climate tailored for material stored there. Visitors can join daily tours of up to 12 people.

I joined a tour led by curator of photographic technology Colin Harding, who says what visitors see in the museum is just a fraction of the collection.

“It’s like an iceberg,” he said. “We can’t possibly display everything, but it’s not a case of ‘out of sight, out of mind.’ We feel strongly that the collection belongs to you, we’re looking after it on your behalf.

“Through Insight, you can go behind the scenes to see the collection, find out how we look after it and how it can be accessed. You can join a tour or, if you contact us first and say what you’re interested in, we can arrange to show you specific items.”

In the print archive, where 300,000 photographs are stored, we noticed a drop in temperature. Colin explained that the emphasis is on preventative conservation, with artefacts stored under controlled temperature, light and humidity.

“We have to strike a balance between preserving the collection and making it accessible,” he said. “Every time you display an image you shorten its life. In our Henry Fox Talbot collection we have the earliest known negative, the latticed window image of 1835, but I’ve only ever seen it twice in more than 20 years.”

Colin opened various drawers to reveal tiny portraits on copper sheets dating back to 1839; examples of the earliest photographic process, the Daguerreotype.

The archive houses collections from the Royal Photographic Society, the Kodak Museum and the Science Museum. Items are also acquired from donations and through the Bradford Fellowship.

“The collections combine to make the most important photographic collection in the world,” said Colin. “What also sets us apart is that we collect the technology to take the images.”

Our next stop was the objects store housing part of an extensive camera collection and 1,000 different TV sets dating back to 1929. There’s even an ‘Audience Reaction Indicator’ which, on closer inspection, turned out to be the famous Clap-o-meter from Opportunity Knocks.

I was fascinated by an old sound projector used to screen early talkies; the film soundtrack, a gramophone record, was placed on a turntable which was speeded up or slowed down to match the action on screen.

Nearby stood a Mellotron sound effects machine, used on 1950s TV drama Emergency Ward 10. By playing its keys, we created sounds such as a barking dog, a train whistle and an explosion. On the wall was a fierce-looking gorilla’s head, designed by Muppets creator Jim Henson for his film, Buddy.

This was an Aladdin’s cave of film and TV technology. The array of cameras and weird-looking contraptions included an early sound mixing desk, an Ealing Studios camera and a 1910 Kinemacolor – a 35mm projector which put colour onto pre-First World War black-and-white films by spinning a reel flashing alternate red and green.

A Zeitlupe camera was used to record V-bomb experiments carried out by Germans during the Second World War. “It was probably swapped for a few Woodbines and it’s ended up here,” said Colin.

Our group included a mother with a couple of children. Her young son was intrigued to discover a chair he was sitting in was designed for taking mugshots of criminals!

It was fun wandering through a honeycomb of corridors, through various doors unlocked specially for us.

The small objects store included cameras of various shapes and sizes, including a wristwatch camera, flashbulb cameras, magic lanterns, slide projectors, even a ventriloquist’s dummy head used in early television development. The Daily Herald archive was of particular interest to me, as it reminded me of newspaper libraries I worked in before the digital age. It contains all two million photographs from the Herald from 1930 to 1969, stored as if it was a working newspaper, in original boxes and filing cabinets. “We feel that historically it’s important to show how pictures were stored in newspapers,” said Colin. “We can find pictures on request.”

I could’ve happily spent hours going through the Daily Herald files. The whole tour had been fascinating, it’s a privilege to see treasures stored behind locked doors. Go and see for yourself.

Free guided Insight tours are Tuesday to Friday at 1pm, and weekends, Bank Holidays and school holiday Mondays at 2pm. To see the collections personally, ring 0870 7010200 to make an appointment.