ROBERT HARDMAN: Dim Lefties may enjoy flicking V-signs at the tycoons quitting Britain for Monaco... But who'll replace the billions they take with them?

Put together, the five golfers next to me at the bar must be worth somewhere in the region of a billion pounds.

There's Richard, who sold his fledgling internet business more than 25 years ago for £30million and has been reinvesting that money many times over ever since. Then there's David, whose family used to own a Premiership club and his chum, Dan, who once owned quite a lot of it, too. Here's Guy, who still works for a living - in private banking - and Nick, who explains that he 'runs investments', his own as it transpires.

I have changed their names but their stories are true and they all have two things in common. First, they are all British and used to live, work and pay their taxes in Britain. Second, not one of them is coming back - except for the odd family gathering or football match.

That's because they now live here in Monaco and are very happy with the place - as are more and more of what the financial sector calls 'high net worth individuals' (and what Labour regards as 'piggy banks'). For the number of British residents here has just reached a record high - 3,100, almost double the number who lived here ten years ago.

What's more, not including the French, the Brits are now the fastest-growing cohort out of all the 144 different nationalities currently to be found in this tiny principality - accounting for around 8 per cent of the 39,000 residents.

Contrary to myth, they are not rich geriatrics plus a few sports stars (although you will see tennis star Novak Djokovic or half of F1 wandering down the street). Indeed, the average age of an adult in Monaco is 47 and the average British new arrival is 44, markedly below the average British adult at 49. And it's coming down all the time.

'We are getting more and more people in their late 30s and 40s coming here with young families because they are already starting to think about issues like inheritance,' says Mark Thomas of global estate agents Knight Frank. Having played rugby for Cambridge, rugby sevens for Wales and the professional game for Nice, Mr Thomas ended up on the Monaco bobsled team with Prince Albert (best man at his wedding) and chose a career in real estate.

After more than 30 years here, he calls it 'the biggest small village in the world' and has seen property prices go up (sales by a steady 5 per cent and rents by 10 per cent) as the ages go down.

'It's about so much more than tax. It's about health, education... and that means the whole family has to like it here,' he explains in his harbour-front office, right above the Grand Prix grid.

The Mail on Sunday's Robert Hardman travelled to Monaco to meet the British billionaires ditched the UK for the principality 

Pictured Mark Thomas who works for Monaco's top estate agency. He claims more and more people in their late 30s and 40s are coming to Monaco with young families because they are already starting to think about issues like inheritance

He and his colleagues are not just estate agents but experts on everything from visas and lawyers to schools and parking (the going rate for a garage space is £320,000; a row of eight just went for £2.2million to a chap who wanted his Ferrari collection in one place).

An £18million deal for a four-bedroom town house is in the closing stages when I arrive. Monaco property averages £56,000 per square metre, nearly twice the going rate for the smartest parts of London, but British buyers regard that as small beer versus the new tax regime in the UK.

'These are usually people who have built up businesses and companies and they have paid all their taxes,' says Mr Thomas. 'Now, they look at what might happen if they are run over by a bus. Suddenly, the family face a fire sale to pay the inheritance tax and so a business is wrecked.'

Over the phone I talk (anonymously) to one British billionaire who has moved here since the election. 'I was happy to pay income tax. But to create a successful trading company, whether it's metal-bashing or hospitality, and then not be able to hand it on to your kids - that's the straw that breaks the camel's back,' he tells me. 'I had to dismantle a lot of trusts and company structures, which would be very complex to renew if I come back. So I don't expect I will.'

In crude terms, a vindictive policy that might pay for, say, 500 nurses, has just driven out a man who was previously paying for several thousand.

These are concerns similar to those of British farmers who have been protesting furiously against Labour's imposition of inheritance tax on farms above £2.5million (an improvement on the original sum of just £1million but still enough to break up many farms).

Farmers, of course, enjoy public sympathy whereas millionaire entrepreneurs do not - and do not expect any either.

Being taken for granted was fair enough. Being demonised for creating wealth while simultaneously expected to underwrite chaotic, uncontrolled public spending is, for many, another tipping point. Look at the latest annual Sunday Times list of top UK taxpayers, published at the start of the year. Since then, the duo at number one, Betfred founders Fred and Peter Done (estimated annual tax paid: £400million), have shifted their property arm offshore to Jersey. Number three, hedge fund boss Chris Rokos (£330million a year), has packed up entirely and gone to Greece.

Antoine de Massy's coffin is taken into Monaco Cathedral. The 29-year-old's body was found in a private park after he failed to appear at a family lunch

Prince Albert of Monaco and his wife Princess Charlene at Antoine's funeral. Antoine was the second cousin of Prince 

Robert Hrdman at a memorial to Antoine near the garden where he died 

Or look at the latest study by the boffins at Bloomberg, which shows that £120billion has left the UK

in the past two years. That is the entire annual UK education budget - or double the defence budget - which has just disappeared. An exodus that began with Tory dismantling of 'non-dom' status for foreign millionaires has now been ramped up by Labour's soaring tax take.

Dim Lefties may enjoy flicking V-signs at the vapour trails of vanishing private jets but who the hell is going to fill a £120billion hole?

And that's just for starters. Add on all the tax that these tycoons will not be paying next year and every year thereafter, plus the workers they won't be employing and the new businesses they won't be starting up in Britain.

As Mr Thomas's Danish-born business partner, Stephan Balkin, puts it: 'We love socialism in Britain because it sends us great clients in Monaco.'

Another major draw is street safety. The recent riots across Europe, especially in neighbouring France, have shocked people here but there is no chance of it spreading to a place bristling with cameras and one police officer for every 60 citizens (it's one per 450 in France).

'Security is second to none. I happily walk home at midnight without a thought,' says Victoria Barker, a British-born tennis pro-turned-senior executive at Monaco's largest hotel, the Fairmont.

Expats tell me that this is one place where they are entirely happy wearing their best jewellery on the street without any fear of a hoodie on an e-scooter.

Pictured: Victoria Barker, Executive Officer of the Fairmont Hotel in Monaco. The British-born tennis pro-turned-senior executive works at the largest hotel in the city-state 

From left to right: Stephen Balkin, Mark Thomas and Sebastien Le Graverend who work at Monaco's top estate agency 

The main issue is space. Monaco has a finite amount, while demand keeps on growing. This summer, for the first time, the local population - known as Monegasques - hit 10,000 with the birth of Anna Ella Carlevaris. Prince Albert and his wife, Princess Charlene, even held a special ceremony to confer a medal on the three-month-old.

Like the natives, so the expat population is at record levels, too. War in the Middle East is making Dubai less appealing while Italy - previously a hotspot for tax exiles - has suddenly stirred things up with talk of a new exit tax. It only adds to the appeal of Monaco.

I drop in at Slammers, a few blocks back from the harbour. Emphatically not a swanky members' club, it is a regular sports bar with English football on the telly and Guinness at £8 a pint. It is here that I meet the group of expats, fresh off the golf course who have no regrets.

'There aren't many places where an accountant can just drop in for a drink with a tennis star, a racing driver and a prince,' says Richard, at which point a cousin of Prince Albert does indeed walk in.

All say that one of Monaco's greatest selling points is political continuity. 'Britain or Italy might be sound one year and then it's all change the next,' says Nick. 'This place doesn't do change.'

If there is one thing that grates with them, it's the old Somerset Maugham line about the Riviera being 'a sunny place for shady people'. 'That's just History Channel stuff,' says Nick.

Except that there will always be shady people drawn to a place where 40 per cent of the population are millionaires. And a dark cloud is certainly hanging over the principality as I stand in the drizzle outside the cathedral watching the entire royal family gather last week to mourn one of their own.

The body of Antoine de Massy, 29, was found in a private park after he failed to appear at a family lunch. His father, Christian, known as Baron de Massy, is the son of Princess Antoinette, the elder sister of the last monarch, Prince Rainier III.

Robert Hardman in front of the Monaco skyline. The main issue in the principality is space. Monaco has a finite amount, while demand keeps on growing

Antoine had dreamed of representing Monaco at the Olympics playing tennis, until a wrist injury intervened. After studying international relations in the US, he had started up a tech business back home.

He was last seen leaving a nightclub in the early hours of October 25 and walking along the Boulevard du Larvotto, a busy main road with apartment blocks above and below. He fell 40 ft from here to his death. A shrine has now sprung up in a small public park above the spot, with candles, tennis balls and a Monaco flag.

A 42-year-old Ukrainian national, resident in Monaco for 30 years, has since been charged with 'involuntary manslaughter and failure to assist a person in danger', according to the authorities, while they are still not ruling out an accident. Having inspected the scene - and viewed the strong railings, hedge and flower bed standing between the pavement and the drop - I am not buying the 'accident' narrative.

The local media keep a respectful distance opposite the Cathedral of Our Lady Immaculate steps as family and friends arrive for the funeral. Prince Albert enters via a side street with his wife and his sisters, Princesses Caroline and Stephanie.

A policeman stands immediately in front of me once my presence has been clocked. Very Monaco. The powers that be want this tragic saga kept low-key.

The Ukrainian connection, inevitably, is a reminder of an extraordinary incident in June when expat Ukrainian financier, Vadym Yermolayev, his partner and his teenage son were badly wounded by a bomb on their doorstep. The alleged hitwoman, Anastasiia Berezovska, another Ukrainian, was caught on CCTV and then found shot dead a week later in a wood near Kyiv.

I find builders completing final touches to the bomb damage at 'Sun's Palace', Yermolayev's elegant town house a block back from the Boulevard du Larvotto. Nothing more to see. Move along now.

In fact, following the invasion of Ukraine, Monaco has bowed to strong EU pressure to root out any Russian funny money. Last month, it was removed from the 'grey list' of the global Financial Action Task Force and given a clean bill of health.

The reality remains that it is very much safer to walk these streets than those of any other European city. Which is why, say all the expats, Monaco is overcoming what was once the main stumbling block. 'It used to be the wives who didn't want to move here,' says one expat of longstanding. 'The men might have deals to do but the women were worried they would get bored. That's just not the case any more with the younger demographic. And most people have a weekend bolthole over the border in France or a yacht.'

There is apparently an ever-growing waiting list for the International School of Monaco (in an alliance with leading London independent, King's College School Wimbledon) while the principality now has more hair salons and spas than ever.

And the developers are raising their game. Mr Thomas shows me a two-bedroom flat in a traditional townhouse five minutes from the harbour. Though just 1,000 sq ft, it's got sight of the sea and has been remodelled by UK designer Guy Phoenix to include a steam room and sauna. Last week, it went on the market at £5million and there's already an interested buyer. Guess the nationality.