Obituary: Alex Cassie; master forger whose war exploits were recorded in the film The Great Escape

Alex Cassie was instrumental in forging the papers that made possible one of the most daring escapes from a German prisoner of war camp.

His meticulous care in forging documents – letters from sweethearts, bills in restaurants and ticket stubs – proved so authentic that Cassie became an integral part in the mass break out from Stalag Luft III in 1944. That was made, with a few cinematic additions, into the famous film The Great Escape.

Forging is a painstaking job and the slightest slip can easily be spotted. Cassie, however, was a fine artist and he brought the disciplines of painting and reproduction to the forging of documents.

He was a generous, unselfish man. Shot down in his bomber over the Atlantic in 1942, he spent the rest of the war in Stalag Luft III. But when it came to his turn to join the escape team, he found he suffered from claustrophobia. Rather than hamper the escape route, he withdrew.

Alexander “Sandy” Cassie was born in Cape Province, where his Scottish parents had emigrated after their marriage. He was educated in South Africa, but returned to Scotland to read psychology at Aberdeen University, graduating in 1938.

He worked for a year in Peterhead on a time and motion study in a personnel department. But with war imminent, he joined the RAF to train as a pilot. He joined No 77 Squadron, which flew Whitley bombers and he was principally involved in flying on bombing missions over France and Germany. Some sorties included coastline patrols into the Atlantic and in May 1942 his squadron was instructed to monitor activity in the Bay of Biscay.

That September, Cassie was on a patrol and spotted a German submarine on the surface. He went in at a very low level to attack and successfully dropped his bombs on its stern. However, his bomber was hit by enemy fire and one engine was badly damaged. He had to ditch his bomber in the sea, where he and his crew were picked up by a French fishing boat. They landed in Brittany, where the German authorities were waiting for them. Cassie was immediately dispatched to Stalag Luft III.

He joined a new escape committee, X-Organisation, which specialised in forgery. With characteristic good humour it was named Dean & Dawson after a well-known London travel agency of the time.

Forgery was at the centre of the escape committee’s operations. If there were any suspicions over the papers, the escaper was either shot or interned. Cassie’s eye for detail and scrupulous patience were to prove vital in the whole process of printing the documents.

The forgers also had to be inventive and employ all the ingenuity they could muster. They bribed guards, so that they had a typewriter with an authentic German typeface. They copied their guards’ documents and printed very passable soldiers’ pay books, identity cards and military passes. Cassie made rubber stamps carved from Wellington boots and Red Cross supplies were used in many imaginative and unexpected ways. Cassie was adept at ageing the documents – usually with cold tea.

During one frenetic forgery session, a lookout spotted a guard approaching. The alarm was passed on and when the guard came in, he found Cassie giving an intense lecture on psychology. In the film, the director needed something more dramatic and when the guard came in Cassie (played by Donald Pleasance) was lecturing on bird watching.

The escape was not the hoped-for success and all but three of the 76 escapers were recaptured and 50 were shot on the orders of Hitler. The Germans issued orders that “escape from prison camps is no longer a sport” and severe penalties were threatened to anyone attempting an escape. As Germany was being slowly surrounded by the invading forces, , in January 1945 the Germans emptied the PoW camps in Poland and Cassie and his fellow prisoners were forced to march westwards in what became known as The Long March. They were liberated by the advancing British troops four months later.

Cassie was demobbed with the rank of flight-lieutenant and initially joined the Civil Service as a psychologist, working mostly in the Air Ministry. He ended his distinguished career in the RAF with the Army Personnel Research Establishment in Farnborough. He retired in 1976 as a senior principal psychologist and was elected a Fellow of the Royal Psychological Society.

In retirement, Cassie furthered his love of art and spent many hours painting. He married Jean Stone in December 1949. She predeceased him and he is survived by their son and daughter

ALASDAIR STEVEN