The post of deputy to the UK prime minister is perhaps the most mysterious in the British constitution, possessing 'no set or binding role', 'responsibility without power' and once not acknowledged to exist at all.

Today, however, the post is generally recognised, and, as this book elaborates, in some circumstances deputies have played a crucial role in the running of the country, not least most recently where Nick Clegg extended it for the first time beyond the whim of the Prime Minister.

Illustrated by archive work, contemporary newspaper accounts, Hansard, assorted secondary sources, elite level interviews, this book addresses the significance of this under-researched role. Arranged chronologically, it creates a typology of deputies and a list of factors with which to benchmark performances of deputyship . It examines the uneven evolution of the position of deputy, from its nebulous origins to a generally much more effective and positive role today, and looks at how incumbents successfully interact with, and influence their political environment and colleagues.

This text will be of key interest to students and scholars of British Politics and political history.