Irish Republican Army

This is the first arrest in decades related to the bombings, after six men were wrongfully sentenced to life in prison for the attack but later released.

Soon after the terrorist attack in London, the Parliament's Twitter account posted a short message restoring business as usual. NPR's Scott Simon remembers another time Brits met terror with calm.

The Protestant cleric who bitterly opposed the IRA later forged an unlikely friendship with senior Sinn Fein leader Martin McGuinness.