When ITV mothballed its hit quiz show Who Wants to Be a Millionaire? two years ago, the retirement of host Chris Tarrant was cited as the reason. But there was another problem, which had more to do with the pulling power of the prize pot than the presenter, and which might help to explain the show’s plummeting viewing figures from the heady days in 1999 when a third of the British population tuned in on Saturday nights: namely, that a million pounds didn’t seem quite as much money any more.

By the time the last celebrity special episode aired last year, there were an estimated 11,000 streets in the UK where viewers – had they tuned in – would likely be watching from a house worth £1 million or more, based on figures from the property website Zoopla. And this week came the news that there are now 715,000 millionaires in the UK, meaning that one in 65 adults is now classed as having a seven-figure fortune. To the show’s titular question, the answer in many British living rooms would now come back: “We already are!”

In the programme’s 15 years on our screens, the great property boom has added to the pool of millionaires more quickly than any quiz show could even if it aired every single night and had limitless lifelines. This week’s figures, calculated by Barclays, show a 41% rise in the number of millionaires in the UK, compared with five years ago, when there were just more than half a million of them, and found that nearly half of all new millionaires (48%) in the past five years live outside London or the south-east.

They also demonstrate in figures what the gradual disappearance of “millionaire” as a standard tabloid prefix has pointed at for some time: that after many decades of being so, a million pounds isn’t the standard marker of substantial wealth in the UK any more.

Of course, with the average annual salary calculated last year as £26,500, most of us will consider any carping about a seven-figure nest egg to be a bit rich. And yet the question remains: is making a million still the significant aspiration it once was? Not judging by what many millionaires admit, usually in private, when they say that having a net worth of a million pounds doesn’t make them feel particularly rich at all.

The great property boom has added to the pool of millionaires more quickly than any quiz show could, especially in London and the south-east. Photograph: Ray Tang/Rex Shutterstock

“It’s not a big figure anymore,” says Simon Cocking, 48, from Leeds, who manages the money of many millionaires in the north-east and is probably one himself. “If I had a client who was worth £940,000 today and over a million in a few months, I wouldn’t even notice it now, or mention it to my colleagues – and we would have done in the past.”

The north-east saw a 50% increase in the number of its millionaires, the joint-largest increase of any region in the UK along with Wales, Barclays found. “You find them [millionaires] in the most surprising places in the north-east,” says Cocking, naming Teesside (“a bit of a smoky place”, he adds) as a hotbed of millionaires who have made their money from heavy industry, oil and gas.

Unlike in London, most of the millionaires he deals with, as the director and part-owner of Leodis Wealth, do not live in their main asset. “I’ve got clients who are asset-millionaires but who are living in ex-local houses,” he says, and even those who live in beautiful homes don’t have their wealth tied up in them, allowing them to multiply their wealth with investments. “In London, my clients typically struggle for cash and liquid investments while on paper they are worth a fortune,” he says, “in the north-east, people are not having to tie up most of their wealth in their home. You can have a lovely house and still make significant investments.”

Cocking says that the cost of a millionaire lifestyle has shot up much faster than the standard measures of inflation, so achieving the millionaire dream of the 1980s would cost a lot more now. He admits he is probably past the millionaire threshold himself, but doesn’t feel what people used to mean when they said “millionaire”. “To go out and buy new Porsches and the rest of it, you need to be pushing double figures in the millions,” he says.

Barclays says healthy returns from stock market investments and entrepreneurial success, as well as higher wages and a better employment rate since the crash, have contributed to the surge in millionaires nationally, but clearly the major driver has been booming property values, centred on London. Tales of wisely holding on to – or foolishly letting go of – three-bedroom terraces that are now worth eye-watering sums are a staple conversation in the capital. According to the Barclays research, the capital has the most millionaires, up 48% since 2010 to 191,000 – more than the millionaire population of Wales, Scotland, Northern Ireland and northern England combined.

To ask one such bricks and mortar millionaire how rich they really felt, all I had to do this week was leave my (rented) house on the southern edge of Brixton, walk around the corner and knock on the first door, a late-Victorian end-of-terrace semi, where businessman David MacIver, 53, agreed to let me in. He and his wife Sarah bought his four-bedroom home for £290,000 in 1999, when the area was considered a “bit fierce” – he says – and there was a squat next door and an anarchist centre at the end of the road. Since then, just by holding on to it he has become a millionaire, with the house now likely to be worth more than £1.5 million.

“We don’t live a millionaire lifestyle,” he says over a homemade latte. “I wouldn’t go and buy a Porsche tomorrow.” Though the couple own and run a production company, called SSP, their wealth is still disproportionately tied up in the value of the house. MacIver says it “gives you more possibilities” for the future scenario when they might sell the house, but that in the meantime it doesn’t help much with paying their two children’s private school fees or London’s high living costs (a problem he’s well aware doesn’t rank high on the leaderboard of human suffering). Most of his friends are in the same boat: “We are the generation that lucked out,” he says.

Being a millionaire in the sense of having a million pounds in the bank, ready to spend, is a rarer experience, but some of those who have had it say it isn’t as life-changing a sum as they thought beforehand. When David Edwards, a physics teacher from South Wales, got the £250,000 question right on Who Wants to Be A Millionaire in 2001 and looked at the cheque, he said: “That’s probably more than I’ve been paid throughout my working life.” A few questions later, Tarrant was shouting “You are a millionaire!” in his ear as confetti filled the studio and his wife Viv cheered wildly behind him.

‘I thought, and I still do, that a ­million pounds is a phenomenal sum of money’ … lottery winner Mark Myatt. Photograph: Graeme Robertson

Now 68, he says he went on the show to win the opportunity to retire early – which he achieved. “I think I imagined at the time that any six-figure sum would be enough to retire and a million would feel absolutely decadent,” he told the Guardian this week, “but I realise now that my rudimentary mental maths weren’t quite right. In retrospect, yes, it has made life a lot more comfortable, and it gave my wife and I an extra five years of retirement, but it’s not enough to live the life of Riley and have extra retirement, too.” He still lives in the same village near Uttoxeter, and spent about a quarter of the money on a plot of land in France. Did being made a millionaire change his life? “It carried a lot more significance then than it does now, having been there,” he says. “I don’t feel that much different.”

The first British winner of the show, Judith Keppel, once said that the best thing about her win was not having to move house. The last British winner, retired civil servant Ingram Wilcox, 71, says that he now lives comfortably but modestly, having been made a millionaire in front of the nation in 2006. He says he gave much of it to his children, and lost some in the crash, but when he won the money it didn’t go as far as he had imagined. “Even at the time I won it, when I started looking round for a house, nine years ago, I saw that quite sizeable areas of Bath didn’t have a house for less than a million. At the time it seemed like an unimaginable amount, but I have learned better than that.”

The first British winner of Who Wants To Be a Millionaire, Judith Keppel. Photograph: REX Shutterstock

Mark Myatt, 46, from Hemel Hempstead, won almost exactly a million on the National Lottery in 2009. “I thought, and I still do, that a million pounds is a phenomenal sum of money. For the average person it would be more than every annual pay packet put together.” He says he was “half way there” before the lottery win, and has used the winnings to build up his property development company with his wife. “I drive a nice little Porsche now, and we’ve been on some very nice holidays. We took the boys out to see Father Christmas in Lapland and we’ve been to Jamaica, Cuba and Dubai.” Does a millionaire still feel rich to him? “I actually feel very privileged to be what people call a millionaire,” he said. “It makes you sort of feel that you have achieved something, that you have achieved what most people aspire to be.”

In the US, where a dollar is currently worth about 65p, millionaire status is a more easily attainable by middle-class people in one generation, and is the subject of hundreds of self-improvement books, like The Millionaire Fastlane and last year’s The Millionaire Within Us. Someone coming across a copy of those titles in 100 years’ time, when a million is just enough to cover college fees, might laugh.

Last year’s Credit Suisse wealth report calculated that there are 35 million dollar millionaires in the world today, and that there will be 53 million in four years’ time, with emerging economies such as India and Indonesia seeing their pool of millionaires rise by more than 60%. Using a slightly different methodology from the Barclays figures this week, and using $1m as the threshold, the report estimated that the UK had 2,043,000 millionaires last year, and forecasted that rising 66% to 3,381,000 in 2019. Only France (2,444,000) and the US (14,166,000) have more.

“This time next year we’ll be millionaires,” Del Boy used to vainly predict in Only Fools and Horses. In the 80s, and in insalubrious Peckham, the prospect of becoming millionaires seemed – to Rodney, the rest of the cast, and the viewers – comically remote. Now, anyone who kept hold of a Victorian terrace in some of the streets where the area’s rapid gentrification is happening fastest will be a millionaire without having lifted a finger, let alone bought into any of Del Boy’s doomed schemes. Luvvly jubbly for them, but would Del Boy be hoping for more these days?