Through most of the 20th century in Canada, power alternated between a 'centre-left' party called the Liberals (equivalent roughly to the Labour Party in the UK or Democrats in the US), and a 'centre-right' party called the Progressive Conservatives. These parties also had provincial equivalents.
This system first began to seriously break down with the rise of the New Democratic Party of Canada (NDP), successor to the Cooperative Commonwealth Federation (CCF), in the 1960s. The CCF arose in Saskatchewan under Premier Tommy Douglas who was also the first leader of the federal NDP.
In British Columbia the NDP was particularly strong and power alternated between the New Democratic Party of British Columbia and the populist BC Social Credit Party at the end of the 20th century. Parties by traditional names, 'Liberal' and 'Progressive Conservative', were marginalized and had little or no role in government. Politics became strongly polarized from left to right, and reflected an instability often referred to as 'frontier politics'.
During the 1992 Provincial election, the ruling Social Credit Party lay in tatters under Premier Rita Johnston. Multiple Socred scandals had left many BC conservatives looking for another option. At this time Gordon Wilson was the leader of the BC Liberal Party, and although his party was practically non-existent in the polls, he insisted he be included in the televised debate between Premier Johnston and NDP Leader Michael Harcourt. The networks eventually agreed, and Wilson impressed many with his performance. The Liberal campaign suddenly gained tremendous momentum, and syphoned off a lot of support from the Socred campaign. In the end, the NDP won the election, but the Liberals came in second with 17 seats to the Socreds' 7. The Social Credit Party effectively died at that point.
In 1995 Vancouver Mayor Gordon Campbell successfully challenged Wilson for leadership of the Liberals. Wilson in turn, accepted a cabinet position in the NDP government.
In 2001 Campbell beat the NDP and was elected Premier, the seventh premier in ten years. He put together a coalition named the BC Liberal Party, which unified federal Canadian Alliance, former BC Social Credit Party, and Liberal Party of Canada supporters. The result is the BC Liberal Party, whose platform resembles that of conservative Democrats or moderate Republicans in the States of Washington or Oregon, but with Canadian distinctions such as proclaimed support for universal health care.
Most Liberals in Canada don't associate themselves with the BC Liberal Party, although cynics say that there is little to distinguish their policies from those of Liberal Party of Canada leaders such as Paul Martin, Jr
See also: Liberal Party of Canada, BC Social Credit Party