Mr Duncan Smith had over-stepped his authority, blurring the lines between the party organisation and the leader's office.

ECONOMIST: Bagehot

At Merrill, board member Alberto Cribiore has stepped in as interim non-executive chairman and is leading the search for a new leader.

FORBES: Street Quakes As Another Chief Falls

The main rival to the 58-year-old Mr Bersani was Dario Franceschini, a former Christian Democrat who stepped in when the previous leader, Walter Veltroni, resigned in February after a disastrous showing in a regional election.

ECONOMIST: The Italian opposition gets a new leader��and a new scandal