Sometimes, one fact goes a long way towards explaining a global crisis. Behind the rubber dinghies laden with desperate people washing up on European beaches and the refugee camps spread across the deserts of Jordan - or, for that matter, the plains of Chad – lies a remarkable figure.

The number of people driven from their homes by conflict worldwide has jumped by 40 per cent since 2013. You have to go back to the early 1990s - the era of the Rwandan genocide and the Yugoslav wars – to find a time when the ranks of the huddled masses rose so sharply in such a short period.

The raw data are as follows: in 2013, the global total of refugees (who have escaped across borders) and “internally displaced people” (who are fugitives within their own countries) stood at 33 million. By 2015, the number had climbed by 13 million to reach 46 million.