No big British company has dared to give the titles of chairman and chief executive to one person, as is commonplace in the US. But whatever the role is called, plenty are experimenting with "non-non-executive chairmen": HSBC, ITV, Cable & Wireless - and now Marks and Spencer.

As plastic bag manufacturers have just found out, where M&S leads, others follow. That makes the retailer's decision to elevate Sir Stuart Rose to executive chairman notable. Whether it should be adopted more widely is another matter.