There are now half a million people over the age of 90 in the UK, according to data published by the Office for National Statistics.

Advisers have said this raises the problem of funding expensive care in old age, which is a "major concern" for some clients.

Data released yesterday (29 September) by the ONS revealed there were 556,270 people over the age of 90 in 2015. That was almost three times the 1985 number of 194,670.

The increase in the number of centenarians was also pronounced, leaping 65 per cent over a decade, reaching 14,570 people over the age of 100 in 2015.

Bev Stoves, a financial adviser with Investment Sense, told FTAdviser her clients were increasingly concerned about the cost of care in old age.

She said: "Most clients are living longer. They're seeing their parents in care homes and they're incredibly aware of the cost of it. And they're worried that will be them."

Ms Stoves said that there were few annuity-style products on the market that addressed the risk of needing care in old age, meaning if clients wanted to avoid going into state nursing homes, they had to provide the funding - and bear the risk - themselves.

This, she said, meant retirements were "U-shaped" - with clients spending more in early retirement, scaling back in their seventies as they became less active, and then spending more in late retirement as the need for care increases.

She added that pension freedoms - which abolished any limits on how fast people could draw down on their pension pots - were potentially "incredibly dangerous", as many people simply do not consider longevity, or they assume the government will provide a comfortable retirement income.

The ONS figures showed that of the centenarians living in the UK, 850 were estimated to be aged 105 or more, double the number in 2005.

Around four out of five people aged 90 and over in the UK in 2015 were aged below 95, but the age structure of the 90 and over population is gradually becoming older.

Gary Nettleingham, managing director of Catalpa Financial Planning, agreed the cost of care was a major concern for his clients.

He said he dealt with it by discussing his clients' health and looking at the "what if" scenarios.

"We consider what will happen if they need long-term care, and the contingencies that you can put in place," he said.

Mr Nettleingham said there was a trend now of taking less income in early retirement. Rather than drawing down 5-6 per cent of their pension pot, he said 3 per cent was becoming a more realistic figure.

He also said his clients were working longer, though he said this could be a challenge, not because people were unable to work that long, but because "the expectation is for people to retire around state pension age".

On the product front, Mr Nettleingham said the decline of annuities - for which he said former chancellor George Osborne bore some of the blame - posed a challenge. Drawdown, he said, introduced sequencing risk into the mix, a problem which annuities were immune from.