This wide-ranging book - one of the first major studies of British radicalism in the years between the collapse of Chartism in 1848 and the advent of Gladstonian liberalism in the 1860s - explains how and why radicalism lost its hold over British politics. The book begins by re-examining the rise of radicalism in the 1830s and 1840s, arguing that it was the 1832 Reform Act which invigorated radicalism, by enlarging the powers of parliament and increasing the need for independent MPs. As independents, between the mid-1830s and the mid-1850s, radicals, alongside other liberals and reformers, were invested with unprecedented influence in parliament, in the constituencies, and in the media. During the 1850s events at home and in Europe undermined the radical ascendancy, and paved the way for the moderate liberalism of the Gladstone years. This is an original and comprehensive revision of mid-nineteenth century radicalism and its influence on the origins of Gladstonian liberalism, filling an important gap in our knowledge of Victorian political history.