Published in January 2006, McGrigor’s book is based largely on Andrew Leith Hay’s Peninsular War Narrative. An Amazon.com review describes the it in the following way. “Intelligence was just as important in the Napoleonic Wars as it is today. Then there was only one way of obtaining it – by spies and informers. The Author uses first hand accounts of three of Wellington’s most daring and successful Intelligence Officers. The three men, all of Scottish descent, were very different in character. One was killed in action and another taken prisoner and after narrowly avoiding summary execution made a dramatic escape. There is a romantic angle too. Their stories skilfully interwoven against the backdrop of the brutal Peninsula War where atrocities were common place. This book gives a fresh insight into Wellington’s remarkable triumph over Napoleon’s armies.”
A review continues as follows Mary McGrigor’s “Wellington Spies” is an interesting addition to the literature on the Peninsular War of 1809-1814. The Duke of Wellington’s survival and success against larger French Imperial Armies in Portugal and Spain was due in significant degree to his skill in gathering intelligence on his enemies. McGrigor has mined the surviving papers of three of his most successful spies for first hand accounts.