As historical units, centuries can be cumbersome and unruly beasts. As series editor of the Penguin History of Britain, David Cannadine probably knows that better than most. He was raised in Birmingham – a city shaped by the mayoral legacy of Joseph Chamberlain – in the 1950s, a time when Britain still had not given up its pretentions of being an empire. His four grandparents, all born in the 1880s, still dressed in Victorian black; Cannadine even goes so far as to suggest that the immediate post-Second World War years might be considered the last phase of the ‘long’ 19th century. Mercifully, he is more disciplined than that, starting his elegant volume with the 1800 Act of Union between Britain and Ireland – a measure prompted by raison d’état in time of war that is not always given the attention it deserves by British historians – and drawing his account to a close in 1906, when the Liberal landslide of that year gave birth to the 20th century’s first great reforming government.