Mr Mansion, a former financial director from Leeds, believes he has a lot to offer but is constantly rejected. 'It's very depressing,' he said. 'I apply for anything that's going, but there are very few jobs that don't have an age limit. They all want 'young, newly-qualified'.
'I saw a job advertised by a pension consultancy, and knowing a bit about it, I spoke to them and they said they would be much too embarrassed to employ me as a clerk when I'm an MA, CA, FCMA, and FCT.'
It is an attitude he finds frustrating. 'I think that if you're still awake and energetic you can bring wisdom to a job that a younger person might not have. I mean you've seen it all before.'
Mr Mansion's predicament is one faced by many in his age group and is the focus of a report published today which examines many of the problems caused by a changing population.
According to Life, Work and Livelihood in The Third Age, launched by the Carnegie Trust, 14 million people in the UK are in the 'third age' - between 50 and 74. By 2031, it says, there will be 46 people living on state pensions for every 100 people working because of improved life expectancy and a decreasing birth rate.
'We are not talking about a social welfare issue,' said Sir Kenneth Stowe, chairman of the report's advisory committee. Demographic factors, he said, meant the shrinking proportion of those working would not be able to support the growing numbers of people relying on state pensions.
The report's main concern was how to enable those in the third age to maintain a healthy and active life, and to contribute to society instead of being a burden on it.
'The growth in healthy life expectancy is one of the great achievements of the century,' said Terry Banks, the director of the advisory committee. 'But there are big areas of problems.'
The report said that although it was understandable that in times of high unemployment younger workers were given priority, there was a need to look ahead to the next century when the 'baby boom' generation retired.
'We really need to start now to reverse the trend of early retirement,' Mrs Banks said. She said she was not talking about keeping people in low-paid jobs, but involving them in different kinds of employment to which the job market was increasingly geared, such as casual or self employment. 'This means life-long education and training,' she added. said. 'This is the area where we must get spending from employers and the Government.'
Elsewhere in the report, the committee said it was less concerned with getting the ear of government than provoking a general debate within society. Formal legislation often led to litigation and covert discrimination, Mrs Banks said, but the report did feel that the situation needed to be monitored.
Life, Work and Livelihood in The Third Age; Bailey Management Services; 127 Sandgate Rd, Folkestone, Kent; pounds 19.50