Misery loves company, so refugees from America's Republican Party should understand that theirs is not the only party that has chosen a leader who confirms caricatures of it while repudiating its purposes. Jeremy Corbyn, the silliest leader in the British Labour Party's 116-year history, might kill satire as well as whatever remains of socialism.

Labour was founded in 1900 to demonstrate that a 19th-century political prophet was mistaken. Karl Marx had proclaimed that meaningful amelioration of working-class conditions could not be achieved by non-revolutionary, parliamentary means. Labour helped make modern Britain into a mostly middle-class, generally temperate nation impervious to exotic politics.

In the 1983 election, the last time Labour flirted with serious socialism, its manifesto was described as "the longest suicide note in history," and a party activist advocated "no compromise with the electorate." The electorate was not amused, and Prime Minister Margaret Thatcher continued residing at 10 Downing Street.