The bizarre surfacing of a German U-boat on the Leeds and Liverpool canal is the talk of the towpath. Helen Carter goes in search of its elusive owner

She sits moored on the Leeds and Liverpool canal and is clearly different from other boats; she is battleship grey for one thing, and has a turret but no windows. Horses and cows grazing in a nearby field seem oblivious to the replica German U-boat in their midst, but shoppers leaving Botany Bay (a converted mill open 364 days a year) all slow their cars to point, gasp and admire her distinctive hull.

The dog-walkers, too, universally approve of this extraordinary, windowless creation. Minutes after I walk up the tow path, a well-built man with white hair and a neatly trimmed beard approaches me – and the mystery deepens.

Newspaper reports claim that one "Admiral" Cyril Howarth, a 78-year-old from Thornton Cleveleys, has spent a cool £50,000 on the canal boat's refit. But sources at the Lancashire Telegraph say the owner is actually a mysterious chap called Steve, who seems to have fitted out the boat for his 50th birthday.

Whatever, the man in front of me, wearing a long overcoat and distinctive white trainers, seems to know an awful lot about the U-boat. It has airlock doors, a periscope that goes up and down, but isn't quite finished yet, and 360-degree video monitors that enable it to be steered from inside. It has sonar and radar systems, infra-red lighting and storage for dummy torpedoes in the sleeping quarters. Its registration number, painted in white on the turret, is U-8047 – chosen for its resemblance to U-BOAT.

"You seem very knowledgeable about the boat," I suggest. "Are you the owner?"

"No, no," the man blusters, lighting a cigarette. "No. Er, my name's . . . Richard."

"Are you sure you're not Steve?" He refuses to say, instead explaining that he has "been down here a couple of times watching the work that's been done over the last few weeks. It is a brand new shell, and not as long as they have said in the papers. It was craned in further up the canal a few weeks ago."

The man says the real owner of the boat "lives in Canada", adding that, "I don't think he wants identifying." No kidding. Then he disappears in an L-registration grey Astra and is not seen again for some time.

The owner, whoever he is, had been more forthcoming in an interview with the local press, explaining that he spent about £50,000 converting the boat, that some of the panels had been used on episodes of Torchwood, and that he hopes to take it to maritime festivals and the Henley regatta.

Later I bump into retired lorry driver Brian Gaskell, walking past with his boxer dog, Eric. "I noticed it about three weeks ago," he says. "At first I thought it was being built for a film, but since then I've been talking to the owner."

Gaskell says he has taken a peek inside and seen the periscope and steering wheel – "but I've never actually been on board. I just looked through the porthole. It must have cost a fair whack. The owner didn't look 78 to me, he was a lot younger." I describe "Richard" and he nods. "That sounds like the same bloke."

Ambulance driver Ken Higham and his colleague Gillian Connolly pause to admire the U-boat. "There are no windows in it, are there?" Higham says. "I can't see why there would be any objections to it from war veterans."

British Waterways says it doesn't have any contact details for the boat, as it is not yet registered with it – which means, technically, it should not be moored here. But the organisation has no objection to the aesthetics of the U-boat.

Dog walker Paul Drakefield, meanwhile, thinks it is brilliant. "When I first saw it, I couldn't believe my eyes," he says. "I thought, 'No, it can't be a U-boat.' But then I walked past and the doors were open, and I could see the panels and buttons inside with flashing lights. It's as good as the real thing."