When a scandal breaks, one question people want answered is: why did no one raise the alarm? Just as many will wonder at the apparent absence of any reporters in the News of the World newsroom prepared to break ranks, so they question why no doctor or nurse blew the whistle at, say, Mid-Staffordshire NHS Trust, now the subject of the second of two public inquiries, where patients were left so thirsty they were forced to drink water from flower vases and hundreds may have died from neglect.

It is more than a decade since the Bristol children's heart surgery scandal broke, in which doctors continued to operate long after their poor results indicated they should have stopped. The panoply of regulation introduced in the wake of Bristol was designed to prevent a repeat, yet critics still speak of a "code of silence" in the NHS. A key reason is that young doctors rely on the good opinion of their consultants for advancement.

Whistleblowing is a particularly fraught topic in the NHS, where lives may depend on it, and the Commons Health Select Committee has announced an investigation. Governments have repeatedly promised protection for whistleblowers, but in case after case the protection proves illusory.

Margaret Haywood was struck off the nursing register in 2009 after she covertly filmed patients who were neglected and in distress at the Royal Sussex Hospital, Brighton for a Panorama programme, and was only restored after a public outcry.

Ramon Niekrash, a surgeon from South London Healthcare NHS trust, was suspended last year after reporting patient safety breaches at Queen Elizabeth Hospital, and was subsequently left with a £180,000 legal bill, despite winning his employment tribunal.

Stephen Bolsin, who first raised concerns about the high death rate among babies having heart operations at Bristol in the mid-1990s and ended up having to move to Australia, co-authored a piece in this month's Journal of the Royal Society of Medicine calling for a US-style system of protection to be introduced, in which whistleblowers are entitled to a proportion of any fine imposed on an employer.

Stephen Dorrell, chair of the health committee, will have to consider whether offering financial compensation will transfer from the profit-led US system to the tax-based NHS. He wants to see the GMC take a tougher line with those who fail to speak out when they see evidence of wrongdoing or neglect.

It is a laudable aim, but tricky, I suspect, to enforce. The practice of medicine depends, more than most activities, on a team effort. Patronage persists and it may prove as difficult to disentangle the professional issues from the personal among those who remain silent, as it often is among those who speak out.