I have been a business journalist, on and off, for nearly a decade and over that time I have attempted to answer a number of critical questions. They have included: what's the best thing to do when your boss enters the elevator? (look at your feet); does gorilla behaviour teach us anything about commerce? (no); and, what do hedge fund managers actually do? (they sit in front of computer screens like the rest of us).

But there's one question I've been trying to answer for years, but failed to do so: what keeps the Aberdeen and Angus steakhouse going? Here is a chain of West End eateries serving woeful food so badly that Jay Rayner, the restaurant critic of The Observer, has described it as having “the mass appeal of herpes but none of the laughs”. A chain that, in 2001, suffered the ignominy of being featured on ITV's Restaurants from Hell, when mouse droppings were found in a tub of gravy. And a chain that has a reputation for being bereft of visible customers. And yet it occupies some of the most high-profile premises in Britain. How does it do it?

Of course, I'm not the first to have considered the conundrum. Some wag has devised a parlour game that involves players forwarding increasingly preposterous explanations, such as the idea that the firm is run by the Mafia as a money-laundering operation, or is financed by the French Government to encourage American tourists to visit Paris. But, if anything, this mass curiosity has egged me on.

Not that I've got very far. Managers and employees have refused to talk. The man behind the 23-strong chain, one Ali Shah, failed to respond to interview requests (he is notoriously media shy). One restaurant expert argued that the chain survived by catering for undiscriminating tourists (which didn't explain the apparent paucity of customers), while another suggested that it was all down to a cheap long-term deal on the premises (for which he had no proof).

In 2003 I was considering the extreme step of extending the investigation into an actual meal at an Aberdeen Steak House, an experience I'd not subjected myself to in years and made additionally traumatic by the fact that I'm a good Sikh boy and hence do not partake of the Holy Cow, when I was saved by the news that the company had gone into receivership with debts of £7 million.

The British media responded to the demise of the chain with the kind of joy that Portsmouth fans reserved for their FA Cup victory last week. Newspapers observed, variously, that Angus Steak House is an anagram of “Gosh! Nauseates UK”, that “Hans Blix and his chemical weapons inspectors would have donned protective suits at the sight of the Angus Steak House prawn cocktail” and that one required a long shower after dining “to get rid of the stench of failure”.

I didn't share this desire to dance on the steakhouse's grave. Not only had Britain lost a national institution but one of our most intriguing national mysteries, a fascinating conundrum right up there alongside the Loch Ness Monster, had turned out to be no such thing.

But then, the other week, on a rare excursion to the West End, I was in the vicinity of Leicester Square, when I noticed something remarkable and strangely familiar: a restaurant furnished with velveteen booths and occupied by a solitary, dead-eyed customer grimacing at something that resembled a steak on a plate.

A Google search subsequently revealed that not only was the Aberdeen and Angus Steak House back - with fresh online reviews from customers complaining about everything from the use of tinned mushrooms to waiters clearing tables before meals had finished - but had been so for five years!

The startling development seems to have been covered by only two publications, one of which was The Estates Gazette, which explained in April 2003 that “a newly created private firm controlled by Noble Organisation, a Gateshead-based amusement arcade operator, had cherry-picked the most prominent Central London sites in the Aberdeen Steak House chain”.

Determined not to let the opportunity to solve business journalism's equivalent of the Roswell UFO incident slip through my fingers again, this week I hit the phones, although it quickly became evident that the Noble Organisation, a family firm best known for owning the Brighton Pier, would make Ali Shah seem as shy as Russell Brand. I rang one of the restaurants and was informed by an Eastern European voice that he was forbidden to give out the head office phone number. Another restaurant gave a contact number, but it was connected to a fax.

A journalist friend eventually proffered Noble Organisation's head office details and I was told by the telephone operator that one Lynne McCarthy would be the best person to talk to. Lynne McCarthy picked up the phone on my fifth attempt at contact and said that David Biesterfield was the best man to talk to. I left a message for David Biesterfield on his voicemail and he called back several hours later.

“Do you handle the Aberdeen and Angus Steak House?”

“Yes.”

“How's business?”

“We are upgrading and refurbishing the restaurants.”

“Great. I'm interested in writing about the brand for The Times. Could you give me an idea how it manages to survive, given the - erm - obvious challenges?"

“We're not ready to talk just yet about that particular business.”

And that was the end of the conversation. Not, admittedly, the most revealing of interviews. But it was when I put the phone down and once again began to wonder whether I should extend my research into paying the firm a visit as a diner that I had a revelation. The Aberdeen and Angus Steak House's longevity is surely due to the low-level but perpetual trade of journalists, all trying to work out how on earth it survives. Think about it. It's the only possible explanation.

sathnam@thetimes.co.uk

Times Recommends

• A new kind of western conservatism
• Georgiana is the wrong role model
• Alaska, where cops don't bother you