Two political parties have, since the last war, won half or more of the Scots electorate in a general election. One was the Scottish National Party, in 2015, with 50 per cent of the vote. The other—and this still occasions surprise—was the Conservative Party (which took in, then, the National Liberal-Unionists): in 1955 it won 50.1 per cent. The Conservatives lost support steadily until the late 1990s, when they seemed to settle at somewhere between 15 and 17 per cent of the vote. Scotland became a Labour-dominated nation from the late 1950s to their last Westminster win in 2010. But…