Sir Martin Sorrell admits his views about working from home may seem old-fashioned. He would prefer staff at digital marketing firm S4 Capital to come in more often.

But he is more open to another modern office practice - bringing a pet to work.

His own dog, a red setter called Ferus, is ambling amiably around the London HQ when The Mail on Sunday visits.

'I'd rather staff brought animals in than work three days a week,' Sorrell says. Working from home had its benefits in the pandemic, he adds, but is now causing 'discernible reductions in productivity'.

Studies may show that people are happier and more productive, but Sorrell says: 'I don't necessarily buy that. I'm 79, maybe I'm old fashioned. I'm generally coming around to the view that time out of the office, lack of interpersonal connection is a real problem.'

Sorrell, like his peers in the City, is also getting to grips with plans being hatched by the Labour Government, with the Budget just days away.

He is worried about plans to hit inheritance tax, capital gains and employer national insurance contributions - and that these changes are coming at the same time as firms also face upheaval in the form of a workers' rights package spearheaded by deputy prime minister Angela Rayner.

'The Government's in a hole,' he says, and has to take 'pretty drastic action' to fix public finances. But is imposing further taxes on wealth creators the answer?

'We hear that the broadest backs are going to have to take the burden - which I wouldn't disagree with. But at some point in time, tax rates become a disincentive.'

Sorrell remembers a time when the top rate of income tax stood at 83 per cent but 'the difference between now and then is people are far more mobile' and can leave the country more easily, he says.

Already, changes to non-dom status - a concession for people who are tax residents of the UK but whose main 'domicile' is abroad - have 'probably stimulated a bit of movement'. The rule allows people to avoid paying UK tax on income or capital gains made overseas, but is being scrapped next spring and Labour has talked about further tightening the arrangements that will replace it.

There is also strong speculation that inheritance tax rules will change. Currently gifts made more than seven years before death are exempt but that looks set to be extended to ten years.

'I think people will leave, won't they?' says Sorrell. Adding to wealth taxes will have 'very significant consequences as it forces people to liquidate assets to pay the tax and/or leave the country'. OT that he has much sympathy for prominent businesspeople

N who move abroad but continue to comment on UK affairs. Ineos's Monaco-based boss Sir Jim Ratcliffe and Sir James Dyson spring to mind, though he does not name them.

People 'who make pronouncements about what should or shouldn't happen in the UK from Monaco, or Singapore, or elsewhere... it's a little bit difficult for them to make those statements'.

Sorrell says he accepts there may be 'two or three years of pain and tough decisions' as Labour have suggested: 'It's a bit like a company that's losing money and you have to cut costs in order to get it into shape and then there's the sunny uplands afterwards.'

But he is worried the action Labour is taking may backfire. He maintains that Labour's workers' rights package, including day one rights for employees, is the party's 'Achilles heel', saying: 'If you ally that with an increase in national insurance contributions, it's going to make people even more hesitant to take people on.'

To boost growth, Sorrell would like to see more incentives for investors - along the lines of some of the tax breaks and investment zones brought in under the previous Tory government.

Without a coherent strategy starting to reap benefits after a couple of years, Labour's big Commons majority could start to look fragile, he says, especially given electoral quirks meant it was propelled into office with just 20pc of the electorate voting for the party.

'If the Tories have a strong leader who knows what could happen at the next Election? Particularly if the plan turns out not to be a good long-term plan.' Who should that leader be - Robert Jenrick or Kemi Badenoch?

'I think Badenoch's a strong leader. She's got firm views and I think she's feisty and I think she's articulate and I think she's tough.'

Sorrell spoke to The Mail on Sunday in between a hectic round of travelling including several stops in the US - where businesses are anxiously awaiting the forthcoming presidential contest.

The corporate world has its hopes pinned on one candidate, he says, adding: 'It's on a knife edge 50/50. The stock market's saying it's Trump, I think the stock market will fall if Kamala wins.

'Business doesn't like to say so but Trump stands for lower tax, lower regulation.'

The Trump bet, with the fall in interest rates, is part of the reason for the US stock market's current high valuations, he says. That is despite the threat of swingeing new import tariffs under Trump - a policy that many, including the International Monetary Fund, think could stifle growth.

'There's obviously a concern about that and the impact on trade and inflation but maybe Trump is using that as a negotiation tool.'

Sorrell is best known for building up his former company WPP into the advertising industry's biggest player. After an acrimonious departure in 2018 he started again with S4 Capital, which operates in the growing digital sector and has grown rapidly by swallowing up companies such as consultancy Mighty Hive and content producer MediaMonks.

But it has had a tough time and recently warned that lower spending from technology clients would hit revenues. Shares have fallen by more than 90 per cent from their peak three years ago.

He says: 'We still have challenges in terms of pulling everything together. We're very tech-orientated. Technology is 50 per cent of our sales and although their ad revenues have been strong, investment in advertising and marketing has been reduced.'

Sorrell had a brush with serious illness last year when he was treated for cancer. Now he is over that, saying: 'All fine. Scans all clear.'

It has not stopped his jet-setting lifestyle, which has recently taken him to the Middle East, California, New York, Detroit and Spain. That is why his dog Ferus is with him.

'I've been travelling, so I haven't seen him for two weeks,' he says.

What does the name mean?

'It's Latin for savage - because he's not,' he laughs.