It is alleged that a consultant psychiatrist, Dr Kypros Loucas, repeatedly breached the Mental Health Act 1983, which is designed to protect patients' rights.
The Act puts limits on how far individual doctors can go in treating patients detained in mental hospitals - in the absence of their consent - without seeking a second opinion from a doctor appointed by the Mental Health Act Commission, the watchdog body set up under the Act.
David Blunkett, Labour's health spokesman, wants a full investigation of these revelations - and others to be made in tomorrow's Independent and tomorrow's Channel 4's Cutting Edge - and is to ask Virginia Bottomley, the Secretary of State for Health, to make a statement on what action she intends to take.
Mr Blunkett said: 'I find these allegations very disturbing. Why was this man allowed to work within the official system up to seven years after these allegations were first made?'
Ian Bynoe, legal director of Mind, the mental health charity, said there should be an urgent independent inquiry, which should also investigate the 'intolerable delay' by the Department of Health - Dr Loucas's employer at Broadmoor for almost 20 years - in failing to deal with complaints voiced in regular reports from 1985 to 1989 by the Mental Health Act Commission.
Dr Loucas, 65, was not sacked from Broadmoor but asked to take early retirement. He was allowed to continue practising in the NHS, and is now treating inmates part-time at Wormwood Scrubs prison in London.
The commission first voiced concern to the Department of Health about Dr Loucas's activities in 1985. According to documentation later sent by commission members to the Broadmoor Hospital Management Team and the Department of Health, which the Independent on Sunday has seen, Dr Loucas sometimes failed to seek patients' consent for treatment when the Act stipulated that he should have. He also failed to seek second opinions on some patients' treatments when those patients refused or were unable to give their consent.
Sometimes, instead of seeking a second opinion as required, he abruptly withdrew medication. The Independent on Sunday has evidence that abrupt cessation of treatment caused at least one patient to suffer unpleasant physical withdrawal symptoms.
Sir Louis Blom-Cooper, chairman of the Mental Health Act Commission, says it was particularly concerned that Dr Loucas was failing to make available documentation concerning the treatment of some patients, which commissioners were entitled to inspect. This was 'an improper approach to his duty to document what he was prescribing'.
The commission noticed little change in Dr Loucas's practices in response to its first complaints. So it continued complaining - eventually to ministerial level in 1987.
Lord Colville, then commission chairman, warned the then junior minister at the Department of Health and Social Security, Lord Skelmersdale, that it was questionable whether Dr Loucas's patients were receiving the protection that the Act was intended to confer, if their consent to treatment was in doubt.
The letter ended: 'I am bound to raise with you again our very serious fear of abuse; and to press you to ensure that something is done, and seen to be done.' Yet, more than a year later, the commission was still trying to get the department to take effective action.
Professor Elaine Murphy, vice chairman of the commission, describes the department's failure to act as 'disappointing'. She says she would have expected patients to have been removed from Dr Loucas's care until he was willing to comply with the Act, or for their care to at least have been shared with other doctors who would ensure that patients' consent was correctly sought.
After four years of pressure on the Department of Health came Dr Loucas's early retirement, but not from medicine. By the beginning of the following year, he was working as a locum consultant psychiatrist at Horton Hospital in Surrey. The manager there was Dr John Wilkins, now medical
director of Riverside Mental Health Unit which is responsible for Horton. Dr Wilkins was a consultant at Broadmoor for 18 months during 1985 and 1986.
Dr Loucas had no formal interview and his references were not taken up, says Barbara Whiteside, chief executive of Riverside Mental Health Unit, because the appointment was only temporary. Until June 1990, the authority used to interview and take up references only for permanent posts.
Last January, Ms Whiteside told the Independent that Dr Loucas would be leaving Horton at the end of the month, because Riverside was appointing a permanent full-time consultant. In fact, Dr Loucas did not leave until August. Ms Whiteside said this was because it had been difficult to fill the full-time post.
Mr Bynoe said: 'Many of these revelations are deeply disturbing.' He said the system should not allow a doctor who behaved as Dr Loucas had to be subsequently employed in the National Health Service. 'If a doctor is found to persistently ignore the simple requirements of the Mental Health Act 1983, his or her fitness to practise has to be questioned. Further, it is hard to see the circumstances in which such a doctor should then be allowed any more to treat detained patients - the most vulnerable - under the Mental Health Act.'
Asked about Dr Loucas's employment in an NHS hospital after his retirement from Broadmoor, the Department of Health referred the Independent on Sunday to a written answer by Tim Yeo, the health junior minister, on 5 June: 'His responsibilities in any subsequent NHS employment would be a matter for the employing body.'
The Home Office said Wormwood Scrubs knew Dr Loucas had been asked to retire early from Broadmoor, but that it had no cause for concern about his clinical performance.
Despite repeated attempts to contact Dr Loucas, he has refused to comment.