For someone who prefers to keep a low profile, sportswear billionaire Mike Ashley certainly has a knack of hitting the headlines. First there was his surprise decision earlier this year to float his retail empire on the stock market, an exercise which saw him personally bank more than £900 million.

Then, in an equally unexpected move, he spent almost £200 million buying up a 3 per cent stake in the German sportswear group, Adidas. The stake is a personal investment, rather than one through his publicly-quoted Sports Direct group.

Now the reclusive billionaire, dubbed "Britain's answer to Howard Hughes", has launched a £133 million bid for Newcastle United football club. The move came after he snapped up the near-42 per cent stake in the club held by the family interests of life president Sir John Hall in a £55 million deal.

Although many Newcastle fans - known as the "Toon Army" - are welcoming the arrival of what they hope will be a free-spending "Geordie Abramovich", the news came as a shock to supporters and sports commentators alike.

Mr Ashley's move came as a particular shock to club chairman Freddy Shepherd, who owns a 28 per cent stake in the club and apparently first heard the news from his bed in a Tyneside hospital, where he was being treated for pneumonia and a collapsed lung.

Pneumonia or not, Mr Shepherd has come out fighting, declaring that he will not part with his stake. However, many believe that he may ultimately be forced to sell his shares, particularly if Mr Ashley, who is reckoned to be Britain's 25th-richest person, wins over the club's fiercely loyal fan base by promising substantial investment in players and facilities.

It is not just in the football world that Mr Ashley's move on Newcastle has created waves. In the City of London, the deal has heightened concerns over just how his retail empire is being run.

Those concerns surfaced even before the company made its stock market debut in February, and a lacklustre trading update recently has not helped. The shares are currently trading some 20 per cent below their debut price.

At the heart of the City's problem with Mr Ashley is the publicity-shy billionaire's unconventional approach to business: although he remains the majority shareholder of Sports Direct, he holds the unusual position of unpaid executive deputy chairman rather than chief executive or chairman.

Neither he nor other board members bother to make themselves available to investors, analysts or the financial press and the lines between his personal interests and the company's appear to be getting increasingly blurred.

The Newcastle move is fraught with potential conflicts of interest - Sports Direct is the country's largest sports retailer while the club also makes much of its income by selling shirts. On top of that, the club's famous black and white striped kit is sponsored by Adidas, which is a major supplier to Sports Direct.

Adidas has been rumoured to be unhappy with the "pile it high, sell it cheap" approach of Sports Direct, which it fears may be damaging the brand.

Mr Ashley is thought to have taken his stake in the manufacturer in an attempt to protect Sports Direct from any backlash.

There are concerns, also, as to how even someone with Ashley's undoubted flair for business will be able to oversee ownership of a football club and a major retail organisation, particularly when he has already angered investors with his disdain for the conventions of the City.

As Mr Ashley battles to secure control of Newcastle in the weeks ahead, his progress will be followed as closely in the financial pages as it is in the sports sections.

Pundits say UK rate heading for 6%

Minutes from the Bank of England's Monetary Policy Committee - the nine-strong team that sets Britain's interest rates - are pored over by economists each month as they attempt to assess the next move for interest rates.

Even deliberations that result in a unanimous vote - as was the case when rates were raised earlier this month from 5.25 per cent to 5.5 per cent - can reveal much about the direction of movements. The bad news for Britain's homeowners is that although there was a decisive 9-0 decision on May's quarter point rise, the minutes also revealed a lively discussion on the possibility of a half-point increase.

This took most economists by surprise - there has not been a half point increase in rates since 1995.

While we may still be spared a half point rise, many economists now believe interest rates are heading for 6 per cent. This is likely to be reached by another quarter point rise, perhaps as soon as June, and another by the end of the year as the bank battles to keep inflation and the housing market under control. Even worse news, unless you're a saver, is that they may well stay there for much of 2008.

• Fiona Walshwrites for the Guardian newspaper in London