Only once, in a lifetime of making speeches, have I become so overcome with emotion that I choked up. It happened at a ceremony last year to mark the 20th anniversary of the Srebrenica slaughter, when more than 8,000 men and boys were shot by Bosnian Serb militiamen after the fall of the town in 1995. (You can watch my thoroughly un-British lapse here.)

My excuse is that I had just been listening to one of the mothers reciting, without histrionics or self-pity, the story of her son’s murder. Two years previously, I had visited Srebrenica, met the survivors, heard the harrowing stories of boys being marked for death because they were tall for their age.