For decades the classic, evergreen BBC comedy Dad's Army has entertained millions of viewers around the world. But the farcical antics of Walmington-on-Sea's bumbling Home Guard platoon camouflage the true military service of some of the actors themselves. Despite their light-hearted appearance, many of the cast saw active service in one, or even both, of the world wars - and much of it far from humorous.

The inspiration behind the sitcom was the experiences of one its writers, Jimmy Perry, who, as a young 16-year-old wannabe comedian, was still waiting for his call up papers when he joined the eager warriors of the Home Guard in 1940. Little did he know how decades later that ribald group of men in the Watford battalion would provide the inspiration which put his name up in lights. Indeed, was it Perry's own goofy gullibility as a teenager that helped form the character of Private Pike?

Also, admitted Perry, the affable Lance Corporal Jones - in real life Clive Dunn, a former prisoner-of-war who served in the 4th Queen's Own Hussars - was partly based on an old soldier Perry knew who had served in the Sudan. This veteran recalled being told by a CO to 'piss on your rifle' to cool it down. Perry went on to serve in India in the Royal Artillery and then later with Combined Services Entertainments.

As a twenty-year-old British Army officer, David Croft was stationed in North Africa when a raft of comical events, including his struggles with a Bofors gun, went on to shape the calamities which befall the Dad's Army troopers! Theatre-mad Derbyshire lad Arthur Lowe, who played the redoubtable Captain Mainwaring, was thin with knobbly knees when he was seconded to the No.2 Field Entertainment Unit in Egypt.

Meantime languid, good mannered actor John Le Mesurier reported for duty with the Royal Tank Regiment complete with golf clubs in his car boot. By 1943 he was ironically enduring life in Deolali (Doolally in India), when he 'had a captaincy thrust upon him' until being demobbed in 1946.

The astonishing bravery of actor and playwright Arnold Ridley, who was denied a DSO and a Military Medal for his actions during the First World War, makes for heart-rending reading. His creation of dear old Private Godfrey won him millions of adoring fans. The classical actor John Laurie - Private 'We're all doomed' Frazer - was also a hero of the trenches. Always dry-witted he once made everyone laugh on set when he remarked: 'I've played every part in Shakespeare, I was considered to be the finest Hamlet of the 1920s and I had retired, and now I am famous for doing this crap!'

That each man, including the mocking Laurie, helped turn Dad's Army into everlasting success will never be forgotten. And why? Well, in reality they had seen war and knew war, and yet always completely realised and understood how the power of laughter is the ultimate triumph.