Peter joined the R.A.F. in 1938 on a short-service commission and was despatched to France when war broke out. After serving with legendary fighter ace Douglas Bader, Peter was posted to North Africa in 1942, where he was forced to crash-land his Hurricane in a minefield. He flew Spitfires on intruder sorties over France before and during D-Day, on bomber escort duty against V-weapons sites and in support of mass daylight raids deep into Germany. Awarded the D.F.C. in December 1944, he also flew as fighter escort to King George VI's Dakota. By the war's end, Peter had flown every mark of Spitfire and Hurricane in the R.A.F.'s inventory.

Peter Ayerst spent eight years as a fighter pilot with the RAF throughout the Second World War, before eventually retiring as a wing commander.