The number of people in the UK working beyond state pension age has almost doubled over the last 20 years according to figures released by the Office for National Statistics.
The organisation said the number of workers over 65 rose from 753,000 in 1993 to 1.4 million by 2011, with the biggest surge coming between 2000 and 2010.
The proportion of over-65s in work rose from 7.6% to 12% over the same period, but did so more slowly due to the growth of the over-65 population as a whole.
Two-thirds of those in employment older than state pension age worked part-time compared to a quarter of those under the state pension age.
The bureau said this showed those remaining in the labour market over state pension age worked fewer hours, possibly because their state pension and other pension arrangements allowing them to fit their work around other engagements.
Of the 1.4 million older workers above state pension age in the UK in the final quarter of 2011, 39% were men and 61% were women.
Approximately two-thirds of these men worked in jobs classed as higher skilled, but almost two-thirds of these women worked in lower skilled jobs.
Of all the jobs carried out by men, the two most common were farmers and taxi drivers while for women, the most common job was cleaners, followed by administration assistants, care workers and retail assistants.
London and the South East were the regions with the highest levels of post-retirement age employment - 14.1% - which the ONS said could reflect the higher living costs and "migratory drift" away from the capital for retired people.
Commenting on the figures, Saga director-general Ros Altmann said over-50s were increasingly planning to work beyond state pension age, often motivated by job satisfaction and the social benefits of work.
She added: "There are however other factors to consider for the increase in older workers, such as those coming up to retirement finding their private or state pensions are not as good as they had hoped - meaning they have to stay at work if they want a reasonable income. This may be especially true for women who may have returned back to work from taking time off and have very little pension provision.
"Generally though, these figures should be seen as an indicator that we have redefined age and retirement. By embracing and in fact welcoming the opportunities of working during part of these bonus years, we can help boost our ailing economy, ensure less reliance on the state and ultimately make retirement more fulfilling."
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