David Prosser: Why M&S investors are watching ITV

Outlook Still no word from Marks & Spencer on a replacement for Sir Stuart Rose, with the retailer yesterday remaining tight-lipped on the subject as it unveiled relatively impressive second quarter figures. We are no closer to knowing who M&S will appoint as chief executive once Sir Stuart steps back into a pure chairman's role next July.

There is time yet, of course, but M&S should be alarmed at the chaos at ITV. The broadcaster is finding that after irritating many shareholders by appointing Michael Grade to the dual role of chairman and chief executive, it is even tougher persuading investors of the merits of its plans for splitting the office back in two.

ITV's difficulty is that with Mr Grade going, it isn't sure whether to recruit a chief executive or a chairman for the job. Candidates for either post understandably want some say in who their senior colleague might be and are loath to sign up without some reassurances.

At M&S, the problem is slightly different. If you have a track record running a successful retail business where you operate autonomously – think of Justin King at Sainsbury's, for example, one frontrunner for the M&S job – why would you consider moving to M&S, where Sir Stuart plans to stay on as chairman for up to a year? You'd rightly expect him to be breathing down your neck at every turn, even if the retailer offers promises about strict limits on territory, or hints that Sir Stuart might not stay on for the full 12 months. In any case, if Sir Stuart was to quit earlier, you'd want some input in advance, ITV-style, about the identity of the new chairman.

That problem is going to make it difficult for the retailer to attract an external candidate of sufficient calibre, which may be one reason why it has begun hinting that an internal appointment is its preference. Unfortunately for M&S, however, leading shareholders do not seem to be convinced about either of the leading candidates within the retailer. Head of food John Dixon is considered inexperienced, while finance director Ian Dyson lacks a certain charisma.

In other words, M&S may be headed for a situation in which external candidates do not wish to be considered for the chief executive's role – note how many putative contenders have already said they don't want the job – and where the biggest shareholders veto the internal choices.

It's hardly the sort of dilemma the retailer would choose to face at any time. But this row is set to come to the boil in the first half of next year, a trading period about which M&S says it is particularly concerned, given the economic outlook. This isn't just any succession problem, this is an M&S succession problem.