This biography investigates the political career and personal character of Henry Addington, 1st Viscount Sidmouth, to determine his effectiveness as a British Prime Minister during the tumultuous Napoleonic era. Philip Ziegler, a noted historian of British political figures, utilizes primary source documents, private correspondence, and parliamentary records to reconstruct Addington's tenure. The work challenges the traditional historical dismissal of Addington as merely a placeholder for William Pitt the Younger, arguing instead for a more nuanced understanding of his administrative contributions and his role in the defense of Britain.

This work is regarded as a thorough and balanced reassessment of a figure often overshadowed by his contemporaries. The text provides a dense, scholarly examination of the administrative challenges faced by the British government during the Napoleonic Wars.