Steady, sensible and conciliatory are the words used to describe Jan du Plessis, the mild-mannered South African who was named on Tuesday as the new chairman of mining group Rio Tinto.

Despite maintaining a relatively low profile, the 55-year old has, by virtue of his position as non-executive chairman of British American Tobacco and two other high-profile board appointments, quietly emerged as a powerful figure in the City in recent years.