By the time he died in 2015 at the age of 106, Nicholas Winton was the nearest British equivalent to a secular saint. His basic story has been told many times. In late 1938, everyone in Prague was braced for an imminent German invasion. When a friend asked Winton to come and witness the developing humanitarian crisis for himself, he set about organising a series of eight Kindertransports, which eventually brought 669 Czech Jewish children to safety in Britain. Though he said little about the rescue for almost half a century, he was eventually “outed” on Esther Rantzen’s television show,...