When Tim Martin, the founder and chairman of JD Wetherspoon, discovered 2½ years ago that he had prostate cancer, he was advised there was no need to inform shareholders. He underwent a successful operation and was able to carry on working, but he admits the health scares suffered by Steve Jobs, the Apple co-founder and chief executive, show that the issue of disclosure is far from clear-cut.

It was difficult to draw up strict rules, Mr Martin said. “Steve Jobs’s situation is unique because he is a unique person doing a unique job in a unique company. It’s a grey area, as every case is different, but it’s really an issue where common sense should prevail.”

News of Mr Martin’s illness emerged only last month. He said that he had sought opinion before opting to keep his own illness private. “The advice was that if you’ve got something that doesn’t impinge on your performance, there’s no need to say anything. Prostate cancer is potentially serious, but, unless you’re very unlucky, it’s not the sort of thing that puts you out of action.”

The secrecy surrounding the swings in Mr Jobs’s health since 2004 have drawn criticism, although the technology giant is unlikely to face regulatory action or an immediate shareholder backlash.

Nell Minow, a corporate governance adviser, accused Apple’s board of failing investors by fumbling the announcements over his health. “Shareholders ... deserve to know how serious his health problems are and what impact his illness and recovery will have on the company’s strategy and operations,” Ms Minow said.

Frederick Rowe, the founder of Greenbrier Partners, a Texas investment fund, said: “The shoe’s on the wrong foot. The board's concern shouldn’t be the sensibilities of management; it should be worried about the feelings of shareholders. Steve Jobs, in the end, works for the shareholders, not Apple’s directors.”

Patrick McGurn, special counsel to RiskMetrics Group, an institutional investment adviser, said: “There’s a feeling that the company always errs on the side of not being forthcoming and over time it’ll have a negative impact on the company’s reputation.”

Under US securities law, companies must disclose any issue that is material to an investor’s decision to buy or sell a share. But there is no rule on whether an executive’s health is material and in the past companies have not announced the death of senior directors.

The legal position for UK-listed groups is equally imprecise and clouded further by a data-protection requirement that a group must secure an employee’s permission to release such information. Julia Tarvin, a lawyer at Watson, Farley & Williams, said that the relevant listing rules were “quite generic” and that illness fell under the requirement to announce “any important changes to the role, functions or responsibilities of a director”.

The Association of British Insurers, which represents investors controlling 15 per cent of the stock market, said that the subject was not a big concern for its membership. One of the most high-profile cases in Britain was that of Sir David Jones, who saved Next from collapse in the early 1990s. Sir David, who lived secretly with Parkinson’s disease for nearly 20 years, wrote in his biography: “It never affected my performance or my determination to find solutions to Next’s problems.”

One company that found itself obliged to make a statement on its chief executive’s health was Barclays. A decade ago it announced the appointment of Michael O’Neill, only for the former US Marine to suffer a blackout that was diagnosed as a symptom of an arrhythmic heartbeat. He had to step down before he even made it to his desk in London.

Jobs’ health diary

October, 2003 Steve Jobs has a rare pancreatic cancer diagnosed; legal advisers say that he has no duty to tell shareholders

August 1, 2004 Jobs e-mails staff to say he has undergone surgery

June 9, 2008 Jobs appears gaunt at Apple conference. Appearance attributed to his vegan diet and an infection

September 9 Jobs makes light of health concerns at iPod launch, opening with a slide, reading “The reports of my death have been greatly exaggerated”

January 5, 2009 Jobs tells workers that he has a hormone imbalance

January 14 Apple says Jobs will step down until June to recover

June 20 Wall Street Journal reports Jobs had liver transplant two months earlier

June 23 Tennessee hospital confirms transplant

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