I wrote 5 Days in May in the weeks immediately after the Cameron–Clegg coalition took office in 2010. As a post-election negotiator for Labour, I had a sense of their enduring historical importance and felt I should relate the tale as I had experienced it.

I did not publish the account at the time because in summer 2010 I was appointed Director of the Institute for Government, a cross-party think tank, and did not wish to return to post-election controversies. Now that I am back in the political fray I have no such inhibitions. Furthermore, the impending third anniversary of the coalition is a moment not only to take stock of the formation of the coalition but also to reflect on the experience of coalition since 2010 and its lessons for the future of the Labour Party in particular.

The book is divided into two parts. The first is the unaltered text of 5 Days in May, which I wrote in June 2010. The second is my reflections on the Cameron–Clegg coalition, on the institution of coalition government more broadly and on the lessons for Labour. My conclusions are that, while coalitions can clearly be made to work in modern Britain, they are not preferable to single-party majority government either as a means of promoting national consensus and unity or as a means of providing strong government able to tackle big social and economic challenges.

This makes it all the more important for Labour to seek to win the next election on its own, as a broad One Nation coalition.