Adonis has worked for a number of think tanks, is a board member of Policy Network and is the author or co-author of several books, including several studies of the British class system, the rise and fall of the Community Charge, and the Victorian House of Lords.
Books in order of publication:
| Parliament Today | 1990 |
| Making Aristocracy Work: The Peerage and the Political System in Britain 1884-1914 | 1993 |
| Failure in British Government: The Politics of the Poll Tax | 1995 |
| A Class Act: The Myth Of Britain’s Classless Society | 1997 |
| Roy Jenkins: A Retrospective | 2004 |
| Coalition Government in British Politics: From Glorious Revolution to Cameron-Clegg | 2011 |
| A Conservative Revolution?: The Thatcher-Reagan Decade in Perspective | 2012 |
| Education, Education, Education | 2012 |
| 5 Days in May: The Coalition and Beyond | 2013 |
| Saving Britain: How We Must Change to Prosper in Europe | 2018 |
| Half In, Half Out: Prime Ministers on Europe | 2018 |
| Ernest Bevin: Labour’s Churchill | 2020 |
