It's become a cliche that inviting a politician into the boardroom is the kiss of death to any quoted company. The losses erupt, the share price collapses and sometimes the fraud squad comes knocking.
This month, for example, a mere 24 hours after Michael Portillo joined the board of BAE Systems, the defence giant came out with dire figures that had traders dumping the shares faster than a Tornado in a tailspin.
However, the record of Ken Clarke, the former chancellor, completely cocks up what I like to know as Tebbit's law (after Norman Tebbit, who had the misfortune to sit in the boardrooms of two of the most woeful corporate disasters - Blue Arrow in the late 1980s and Sears in the late 1990s). Clarke is becoming something of a lucky charm for share market punters. His tenure at BAT Industries, the cigarettes company, has coincided with a fantastic run for the shares. Out of favour during the dotcom boom, they have since tripled in price.
Now Alliance Unichem, the once obscure drugs wholesaler that Clarke chairs, is coming good. The company is about to enter the FTSE 100, the club of Britain's biggest blue chips.
So my refined theory is that the more right-wing the politician, the more likely the company is to get into trouble. It is, on the whole, the floggers, the swivel-eyed free-marketeers and the more fanatical Eurosceptics who nail their colours to the dodgiest barques.
I think of John Redwood and his chairmanship of Murray Financial Corporation, which was supposed to buy sleepy building societies and transform them by injecting private sector disciplines and ideas. Murray's shares are languishing at 2.5p, compared with 15p two years ago. And this month, Lord Young of Graffham, the former trade secretary, pleaded pressure of other commitments as he left IndigoVision, a whizzy video technology firm he had joined as chairman just eight months ago.
Young was Margaret Thatcher's favourite minister. "Others bring me problems," she once said. "David brings me solutions." Alas, Young's miraculous problem-solving ability failed to help IndigoVision. During his rule, its share price collapsed from 120p to 19p.
The wets of the Thatcher period appear to have chosen more solid companies: Geoffrey Howe at Glaxo Wellcome, Kenneth Baker at Hanson and Douglas Hurd at Royal Bank of Scotland.
I'm not sure how the most notorious company directorship in Westminster - Lord Wakeham's walk-on role at Enron - fits into this theory, since nobody seems able to give an exact account of Wakeham's political views.
These should be glorious days for the alternative business sector. Shareholder-owned companies are not looking so clever. After the Enron, WorldCom and Tyco scandals in the US, and Marconi over here, it is clear that the conventional PLC can be hijacked by its own management, to the detriment of employees, customers and shareholders.
I've been talking to two of the most vocal champions of alternative business models: Sir Stuart Hampson, chairman of the John Lewis Partnership, Britain's biggest worker co-operative, and Mervyn Pedelty, chief executive of the Co-operative Bank and the driver behind its online banking offshoot, Smile.
Both were in good heart. Both believe recent events in the mainstream corporate world - sliding share prices, boardroom greed and out-and-out fraud - can only be good for co-operatives. But each has challenges of his own. Hampson is trying to get a quart out of a pint pot. He's not making enough profits to maintain both the staff bonus - the key barometer of John Lewis's health - and the ultra-generous pension scheme. He also needs to find lorryloads of cash to bankroll a new home delivery service.
Over at the Co-op Bank, the ethical stance is paying off in spades. Customers are flocking in. But the parent Co-operative Group wants to merge the bank with the Co-operative Insurance Society. Pedelty is to run the combined operation. It is being billed as a merger of equals with no job losses among 14,000 employees. But mergers of equals are notoriously difficult. Turf wars ensue. Obvious cost savings aren't pursued. Pedelty will need all his management skills to stop this marriage turning into an inefficient fudge.
Carphone Warehouse is having trouble with robbers; most weeks at least one of its 460 UK shops is turned over. So on a visit to its gleaming new megastore in London's Oxford Street, complete with polyphonic ringtone dome (don't ask), I was unsurprised to see no fewer than 15 CCTV cameras.
Good security? Er, no. The cameras are to record customer movements and shopping habits. Every moment's browsing, rumination and wallet-fumbling is screened on the directors' floor back at the west London head office and analysed from all angles.