Bottom Line: Out of Storehouse

THE AVERAGE tenure of the three executives promoted to joint managing directors by Marks and Spencer last month was 23 years. Ann Iverson has been with Storehouse for just four years and four months, but she was its second-longest-serving executive director. Her departure will cut the average tenure to less than 10 months.

An injection of new blood can help to revitalise performance, but Storehouse has clearly had too much of a good thing. Its shares have underperformed the market by 10 per cent in the past five years while the predictable Marks and Spencer has outperformed by 80 per cent.

Ms Iverson does appear to be simply taking up the offer of a better job in her own country rather than fleeing a disaster. She has converted a pounds 3.9m loss in the year before her appointment to an expected pounds 9.5m profit this year. But at about 3.4 per cent Mothercare's margins are still unacceptably low.

Her departure - like that of David Dworkin, the previous chief executive who took her with him from the US - demonstrates the risks of recruiting corporate fixers, especially from foreign countries. As soon as Mr Dworkin had produced some improvements, he headed back clutching pounds 3.2m. Ms Iverson may not be taking quite as much money but she clearly believes that the challenging job is over. She will also be aware that Keith Edelman, who took over as chief executive last August, is eight years her junior, making it unlikely that she will ever get the top job.

Mr Edelman was too cautious to claim that the board departures were now over. Shareholders will hope he can find a way to prevent them.