What does the spread of street protests across Iran mean for the oil market? The immediate response, driven no doubt by the substantial amounts of speculative money that are in play, is likely to be an upward spike. But although the troubles are serious and fuelled by real hardship in a struggling economy, there is no objective justification for any increase. If anything, the demonstrations can be seen as the prelude to a fall in prices.

The first point in support of this argument is that the protests are based in the country's cities and towns and not, so far, in the oil-producing regions. The disturbances in the southern port of Bandar Abbas are serious but there has been no report of any trouble near the Abadan refinery. Stories of an attack on pipelines in the south by Sunni Islamist jihadis have not been confirmed. As yet, there is no immediate reason to think oil production will be interrupted.

The second point is that the overriding drive of every Iranian government over the last 38 years since the 1979 revolution has been to stay in power and preserve the Islamic Republic, even if that involves making sudden and radical changes in policy. And in this they have been remarkably successful and remarkably pragmatic. As any visitor to Tehran will notice Iranian society, below a thin theocratic layer, is open and, within limits, tolerant of different views. The country has a partial democracy in which real votes are cast.