By Domination or by Default?

A brief overview of modern British political history rather belies the assumption that two main political parties regularly alternate in power at each general election. The reality is more a case of one party dominating over a spell of around three or four elections only to be replaced by the other. To take the recent past, the Conservatives under Margaret Thatcher and then John Major won four consecutive general elections between 1979 and 1997, while Blair’s ‘New’ Labour Party went on to win the next three. The late Victorian period witnessed a similar period of oneparty dominance followed by that of its rival. Thus the Unionists were in power for all but three years (1892-5) between 1886 and 1905, while the Liberals (with their electoral allies the Labour Representation Committee, after 1918 the Labour Party) held office from 1906 to 1915. What factors best explain why one party frequently dominates the political scene, only to be followed by the other? More specifically, why did the Unionists, rather than their arch rivals the Liberals, hold sway between 1886 and 1906?