The findings come from the Retirement Sentiment Index report for Retirement Advantage, which cites surveys including a 2017 Censuswide poll of 1,005 over-50s yet to retire who have private or defined contribution pensions and a YouGov survey in 2016 of 1,001 UK over-50s with a DC pension but not yet in retirement.

Out of the 49% over-50s who will continue in employment, 43% plan to switch to part-time work, while 6% do not think they will ever stop full-time work, up from 4% in 2016, said the report.

Retirement Advantage said if half of those turning 65 this year chose to stay in work they would contribute £7bn annually to the UK economy, a figure made up of £1.6bn from those working full-time and £5.4bn from part-time workers.

Surprisingly, says the financial provider, more than half of older people (54%) say their reason for continuing to work past state pension age is simply that they enjoy working, according to a survey conducted by Censuswide in March 2017 of 1,013 over-50s who are yet to retire.

The next most common reasons include the sense of purpose (53%) work provides, avoiding boredom (52%) and an urge to ease into retirement (42%).

Retirement Advantage added that contrary to popular opinion, the need for extra money comes in only fifth (41%) as a reason for continuing to work. Women are more likely to be motivated by this than men (46% compared to 37%).

Andrew Tully, pensions technical director at Retirement Advantage, said: “This generation will continue to make a significant contribution to the economy in the future and employers will need to consider how best to adapt to this changing employment landscape.”

But Retirement Advantage also warned about the size of the minority who plan never to stop working and the rise in the fraction of working people they represent. Mr Tully said: “This may be perfectly reasonable for some people but it may also reflect a growing pressure to work to be able to pay the bills”.

Another area of concern is that plans to work beyond retirement may have an impact on pension savings.

According to a 2017 online poll by Censuswide of 250 over-55s, 37% of working people who have withdrawn cash from their pensions since April 2015 have continued to pay into a pension and 19% say their employers have. However, 67% are completely unaware of the Money Purchase Annual Allowance (MPAA) limits, says Retirement Advantage.