Inspector Manley told his senior officers he was leaving the force to become a solicitor. A year later he had swapped his truncheon and warrant card for a pinstripe suit at the top City law firm Davies Arnold Cooper.
His pounds 40,000 salary was halved overnight as he began his new career working alongside much younger trainees fresh out of law school.
"I wanted to put my legal qualifications to better use and join the fraud squad," Mr Manley said. "But my senior officers just kept giving me more administrative work to do. I got more and more intensely frustrated. Eventually I thought, if I don't go now, I never will."
Davies Arnold Cooper has already recruited a doctor and a naval officer who have both retrained as solicitors. But Inspector Manley was the first to take advantage of a trust fund set up by the firm in 1997 to provide financial assistance to other professionals who wish to retrain as solicitors. The scheme offers applicants pounds 5,000 to cover the costs of a mid-career change. Mr Manley says that apart from his law school fees he still had to keep up his mortgage repayments and living costs.
Davies Arnold Cooper is typical of a growing number of City businesses and institutions which see value in the life skills and experience of other professionals.
The accountants Arthur Andersen and the high-street bank Lloyds-TSB both have an open door policy to mature entrants who have followed alternative career paths. Arthur Andersen says it has a wide variety of personnel who have acquired skills in other industries before joining the firm. In its communications and entertainment department one of the partners is a former IBM senior sales executive and another accountant, not a partner, is a former professional musician.
A spokeswoman for Lloyds said that in stark contrast to the allegations of ageism made against certain parts of the financial sector, an applicant's age was not an issue when the bank was appointing trainee branch managers.
The Church of England has traditionally been receptive to people who have had other careers before dedicating their lives to God. The Rev David Powe, 47, a former photocopier salesman in London, became a vicar in the late Eighties. His change-over was triggered when he discovered that the company he was working for had turned back the clocks of its second-hand photocopy machines to mislead potential buyers as to their age.
"When I found out that they were giving me these photocopiers to sell, I decided I wasn't going to have anything to do with it," said Mr Powe. "I began to think that I didn't want to get to 50 and wonder what I had done with my life. I wanted to make a difference now." Shortly after he gave up his four-bedroom house and salesman salary to become a prison chaplain.
But not all professions make it quite so easy for people to switch careers. Eve Jacobs was 36 and a deputy head of a Coventry secondary school when she decided to follow her life-long ambition to become a doctor. Now 59, she is a GP in Manchester. "I remember thinking I was half-way to my three score years and ten. I had been told at school that I couldn't do sciences and so would never be a doctor. But I decided I should have one last try."
She applied to every medical school in the country and by return of post had been rejected by all but three. Finally Manchester Medical School accepted her and, after she sold her horse box and Land Rover to pay for her tuition fees, Ms Jacobs settled down to six years of medical study. "I don't think it's any easier now for mature students to retrain as doctors," she said. "I certainly haven't met anyone who made the change at an older age than me."
Because of the strenuous nature of the training and the arduous hours associated with hospital and community medicine the medical profession has always suffered high "wastage" rates. In a recent report, the Medical Workforce Standing Advisory Committee said the dropout rate for medical students was at least 12 per cent. And General Medical Council surveys have shown that half of these students leave because they do not wish to follow this career path, rather than for academic reasons.
Many doctors or medical students looking for career changes end up in the City. This is equally true of the police force, where officers can find lucrative work as fraud and security consultants.
Mr Manley has no hesitation in recommending that fellow dissatisfied police officers follow his lead and retrain. "I had 27 years as a police officer. But overnight I have gone from a negative environment, where there was not enough emphasis on the protection of the public, to a positive one where the client is given as much support as possible. I really do feel I am working for the good guys."