“…Starting as early as Lowell (1902), scholarship has focussed on the 19th century as a transitional time during which party cohesion-and thus the Westminster system-took hold in the House of Commons (e.g. Bagehot, 1873Bagehot, /2011Trevelyan, 1922;Aydelotte, 1963;Berrington, 1968;Cromwell, 1982;Cox, 1987;Jenkins, 1996;Rush, 2001;Schonhardt-Bailey, 2003). While researchers have come to a clear consensus that discipline did indeed increase, the central question of why MPs became more cohesive has lacked a convincing answer.…”