Ten years ago, on March 11 2004, a jihadist group detonated bombs on four trains heading into central Madrid during the morning rush hour. 191 people were killed and nearly 2,000 were injured. It was Europe’s second-biggest terrorist attack after the 1988 Lockerbie bombing. The attack has left its mark both on the people of Madrid and on Spanish society as a whole, as Guy Hedgecoe reports.