The record of the intelligence world in the last few decades has been a mixture of spectacular failures and Hollywood-style successes. Some of the successes have led to breathless newspaper headlines, the most notable of which followed the killing of Osama bin Laden on 2 May 2011. Some of the failures had consequences that were devastating and embarrassing, the most obvious examples being the justification for the invasion of Iraq in 2003 and the series of catastrophic errors that allowed the 9/11 attacks to succeed.

Intelligence is not an easy game. It requires patience, insight, cunning, astuteness, courage and a long memory. It also attracts individuals of unusual character, men and women who are good team players but also exceptionally capable and creative on their own. Sometimes, the best intelligence achievements are a result of persistent and highly motivated undercover endeavours by officers acting alone, often beyond the boundaries of political control.

Mark Huband, always a thoughtful and intrepid reporter when working for the Financial Times, has brilliantly captured the stunning and long-enduring efforts made by two Secret Intelligence Service (SIS) officers who separately helped to lay the foundations for the end of the violence in Northern Ireland. Frank Steele and then