For more than a century, Scotland Yard’s “Black Museum” has catalogued artefacts from the most gruesome crimes of London — and the exhibits have been considered too horrible to be shown to the public.

Generations of police officers have been granted access to its dimly lit rooms, to see the ghastly relics. For almost everyone else, it has remained off limits.

This restriction in the name of public decency may be about to end. Boris Johnson, the Mayor of London, is backing a plan to turn some of the exhibits into a tourist attraction, a museum to celebrate the capital’s emergency services.

The Black Museum includes objects from the Jack the Ripper and Dr Crippen cases — Crippen was in 1910 convicted of murdering his wife and disposing of the body in a bath of acid — and a horrible pair of binoculars.

Brian Coleman, the chairman of the London Fire and Emergency Planning Authority, is working with the mayor on a plan for the new museum. “The police are quite jealous of some of the information they are allowed access to,” Mr Coleman said. “And to be quite truthful, some of the items are just too gruesome for members of the public — but if we had a Black Museum, we would have tourists queueing round the corner.”

In 1869 Parliament gave the police the authority to retain certain items of prisoners’ property for instructional purposes. An Inspector Neame initially gathered together a collection for training purposes, and the first visitors — the top brass at the Yard — inspected the museum in 1877. When that same year a journalist was denied access to the collection, he named the collection the Black Museum in his subsequent report. The name stuck.

It is currently housed in two rooms on the second floor of New Scotland Yard, overseen by Alan McCormick, a retired police officer. The lighting is dim to avoid bleaching exhibits.

The oldest exhibit is a pair of handcuffs used in 1841 to restrain a mutineer. There is weaponry, including swords concealed in walking sticks — and the poisoned umbrella used in 1978 to kill the Bulgarian writer and dissident Georgi Markov on Waterloo Bridge.

A briefcase designed to fire a poisoned dart into witnesses on the steps of the Old Bailey — former property of the Kray twins — is also in the collection. They never got to use it.

Then there are those infamous binoculars: when the lenses are screwed into focus a pair of spikes shoot out to blind the user.

Among the more recent exhibits in the museum is the bloodstained uniform worn by PC Keith Blakelock, the officer killed in the Broadwater Farm riots in Tottenham in 1985, and a section on the serial killer Dennis Nilsen. Parts of the bathroom in which Nilsen hid bodies are in the Black Museum.

For the moment, such artefacts are seen only by police officers and associated professionals as part of their training. MPs and ambassadors have also visited.

The idea is that items would go on display in a “Blue Light Museum”, alongside artefacts from the history of the London ambulance and fire services.

Yesterday Andy Hayman, former Assistant Commissioner of the Metropolitan Police, broadly endorsed the mayor’s plan for an exhibition, describing the museum as “the Madame Tussauds of the Yard”.

Mr Hayman said: “I was rather apprehensive the first time I visited the museum. I wondered if I was being voyeuristic and disrespectful to the victims and their families.

“After a few moments, however. those concerns were replaced with fascination and interest.

“This museum presents such well-kept artefacts of significant historical value it seems a shame the general public do not have the opportunity to have this experience.

“The mayor’s bid to give access to the general public should be encouraged, providing we do not lose sight of our respect for the victims and their families.”

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