Regionalism is the driving force behind their being minor parties in the Canadian and UK legislatures (Australia does not use FPTP).
Canada is essentially five or six different regions mashed together. Each region has a FPTP system with 2 major parties, it's just not the same two everywhere. In Ontario and the Atlantic it's the Liberals & Conservatives, in Quebec the Liberals & the Parti Quebecois, on the prairies the Conservatives & NDP, on Vancouver Island it's the NDP and Greens.
Likewise, UK is generally Labour and Conservative, but the SNP are big in Scotland, Plaid Cymru in parts of Wales, and of course something else entirely is going on in Northern Ireland.