William Cantelo, a 19th Century inventor rumoured to be working on an early version of the machine-gun, left his house one day and never returned. What happened to him, asks Steve Punt.
In the early 1880s, the residents of Bargate Street, Southampton, were probably a bit fed up with one of their neighbours.
From the cellar beneath the pub run by William Cantelo would come the sound of rapid gunfire.
Cantelo, an engineer and gun-maker, was experimenting with a new type of gun. Nobody knew what it was, but it produced shots in quick succession. It was clearly not your average rifle.
One day, Cantelo announced to his sons - also engineers - that he had perfected his new invention. It was a machine-gun, a weapon which used the energy of explosive recoil to load the next bullet. It would fire continuously until the bullets ran out. It was revolutionary.
Cantelo and his sons packed it away into cases, and Cantelo went off, presumably to sell it. He frequently travelled on sales trips, as a successful builder of - among other things - ships' capstans, and other bits of marine engineering.
William Cantelo was never seen again.
Flash-forward to November 1916.
As millions of Europe's young men were busy machine-gunning each other to death in World War I, the inventor of the weapon died, a very rich man and a knight of the realm. His invention had revolutionised warfare - the centuries-old infantry advance became useless, as it could be simply mown down.
Consequently armies retreated into trenches while the generals worked out how on earth to fight this new kind of war. The man who had brought about this murderous step-change was quietly buried in a south London cemetery.
His large and impressive monument contains no indication of what he invented. But his name is written in large letters - Sir Hiram Maxim.
Maxim is not just credited as the inventor of the rapid-firing, belt-fed gun - it bore his name. The Maxim Gun was the weapon of choice of the late-Victorian and Edwardian era, bringing industrialised efficiency to the business of killing people.
To use the phrase compulsory to all documentaries - it "changed the world forever". (Everything in TV documentaries always "changes the world forever", whether it's flush toilets or a new type of hat pin. But the machine-gun really did.)
But what happened to William Cantelo?
What we know of his story originates from a column in a local newspaper in the 1930s, when various witnesses were still alive. The article contains a photograph of Cantelo. And Maxim and Cantelo look uncannily similar.
When Cantelo's sons saw a photo of Maxim in a newspaper, they were amazed. It was the image of their missing father. They tracked him down at Waterloo station, and shouted "father!" at him. As they told it, they tried to approach him, but his train pulled away.
Cantelo, though, seems to have vanished off the face of the earth. His family engaged a private detective to look for him, who supposedly traced him to America - but then the trail went cold.
A large sum of money was withdrawn from his bank account, but the bank in question long ago ceased to exist, and there is no record of where the money was sent or where it was withdrawn.
To complicate matters, both Cantelo and Maxim had large Victorian beards. The late Victorian era was not kind to the art of facial recognition, since most males over 30 sported luxuriant facial hair and all tend to look like a cross between Charles Darwin and a stern Santa. It seems likely, however, that the newspaper photograph captioned as Cantelo is, in fact, Maxim.
This doesn't, however, explain what happened to the vanishing gun-maker.
Cantelo certainly existed. He was well-known in Southampton. Gun-making ran in his family - there are numerous Cantelos, earlier in the 19th Century, who made various improvements to rifles, and at least one of them moved to America. Maxim, on the other hand, had come to Britain from America, where he had made enemies by arguing with Thomas Edison over who invented the light bulb, and generally making a nuisance of himself.
Maxim also complained - in his autobiography - of a "double" who was going round the US impersonating him. Was this Cantelo? Or was it Maxim's own brother, who also looked very similar, and also sported an enormous beard?
There doesn't seem to be any reason why the various witnesses should invent the tales of nocturnal gun-fire beneath the pub in Bargate Street. Cantelo may well have been working on a machine-gun, although the type of gunpowder used at the time would have produced too much smoke to make testing in a cellar very feasible.
What is really intriguing is whether Cantelo and Maxim ever met, and there is evidence to suggest that they did.
The daughter of another Southampton marine engineer called Philip Branon, wrote a letter at the time telling how Maxim had come to Southampton to see a type of propeller her father had invented. He had told his staff not to show it to him, though, because Maxim - she says - had "a reputation for brain-sucking."
This wonderful phrase clearly suggests a tendency to plagiarise ideas. But this is surely typical of how inventors see more successful inventors. It is, however, intriguing. It shows that Maxim did visit Southampton, and was meeting local engineers.
So what did happen to William Cantelo? Did he realise he'd been pipped to the post by Maxim, and come to a bad end trying to sell his own version of the gun? Or was there some Victorian melodrama going on underneath it all, a mistress or similar entanglement, leaving his family looking for reasons to explain their father's sudden departure?
It's a mystery worthy of Sherlock Holmes.