Back to the backstop

As the prime minister walks up the main staircase in No. 10, he or she must pass the portrait of every previous occupant of the office. It is the British equivalent of the slave standing behind the Roman general and whispering ‘Remember you are mortal’ because the career of nearly every prime minister, no matter how distinguished, has ended in failure.

Theresa May must find two of these portraits particularly haunting. Robert Peel passed the repeal of the corn laws in May 1846 with the backing of the Whigs and others, but was then forced to resign as prime minister the following month as the Tories split. Ramsay MacDonald, the first Labour prime minister, was persuaded that a minority government couldn’t deal with a national crisis and so formed one of national unity in 1931. To this day, he is still reviled by his own party.

Peel and MacDonald provide a reminder of what happens to prime ministers who rely on opposition votes to pass their defining legislation for them.