Two Corbyns descended on Downing Street today as Westminster was treated to a family reunion. The first, the better-known Jeremy, was there to hand in a petition with nurses and MPs calling for a 15 per cent pay rise for health workers. The second was older sibling Piers, the ever-eccentric disseminator of anti-vaccine materials, who earlier in the afternoon had shouted about his ‘unconditional support for my brother’ outside the nearby Labour party head office.