This is the point in the cycle when businesses that claimed they would sail serenely through an economic downturn suddenly find themselves on the rocks taking in water.

Death may be certain, for example, but the funeral business is not such a sure thing. American undertakers are reporting that customers are trading down on caskets and switching from top-of-the-range burials to cheaper cremations.

Back in February Arun Sarin, Vodafone's chief executive, said that the mobile phone giant would be resilient but not immune. It turns out that it is not even very resilient. Yesterday it was forced to admit that this year's revenues were likely to be at the bottom end of expectations.

This should not have come as a great surprise. These days, we tend to assume that talking on our mobile phones is as vital as breathing. Surely the phone would be the last thing to be cut - but that is what many people thought about fixed-line phones 20 years ago, and BT's call volume growth slowed dramatically during the downturn in the early 1990s.

But Vodafone could be forgiven for not predicting that Spain would fall off as far and as fast as it has. The collapse in construction after the bursting of Spain's spectacular property bubble has thrown thousands of builders out of work. Many were migrants who have now left the country - and Vodafone's network. In Spain, Vodafone is very strong among small businesses so was particularly exposed to this exodus. It is more upmarket in Britain, so the impact of the building downturn has been less marked, but still noticeable.

On top of that, it is being squeezed by stiff competition.

The cynic would naturally assume that Mr Sarin saw this coming at the end of May when he announced that he was stepping down as chief executive after five years. At the time, the judgments on his tenure were generally favourable. They might be less so now, after yesterday's plunge in the share price, which is now 20 per cent lower than when he announced his exit. But, to be fair, the fall-off in Spain has been very steep and very recent. The share price tumble yesterday might look excessive. After all, Vodafone maintained its profit outlook, partly thanks to lower new handset subsidies and continued cost reductions.

Growth remains robust in most emerging markets, such as India, and there is no sign yet of a slowdown in the United States, although today's AT&T numbers will be closely watched. But investors' nervousness is understandable and there is no doubt that Vittorio Colao, who takes the helm next week, faces some heavy weather.

He will not be the last new chief executive who finds the winds are set less fair than he expected.

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