3. Never underestimate the strength of women

If the female characters in Dad’s Army formed their own platoon they may well knock the old chaps for six. The terrifying Mrs Pike, lover of Sgt Wilson and doting mother to Private Pike, has no truck with Mainwaring’s pomposity and can’t see why Hitler shouldn’t wait until her little boy has clean socks on before invading. The widowed Mrs Fox has ways of extracting pork chops from Jones the butcher (“It’s a purely Teutonic arrangement” he says) and her wig alone would have made the Nazis think twice. And then we have Elizabeth Mainwaring herself, who “disapproves of fun” and spends her entire time off-screen sulking in the Anderson shelter or slamming the phone down on Mainwaring as he tries to appease her.

4. Ignorance might just be bliss…

Private Frank Pike, frequently dismissed by Mainwaring as a “stupid boy”, is naïve, mollycoddled and obsessed with the cinema. He’s the classic perennial schoolboy, like Bluebottle in The Goons and Arthur in Cabin Pressure. “Mum! Can I have a glass of water? Kitchen water, not bathroom water.” He’s permanently bewildered by the fact that Sergeant Wilson seems to have ‘popped in’ to see his mother in the middle of the night. Bless.

5. Honesty might not always be the best policy

It was all about 'being like dad and keeping mum' during World War Two, with careless talk costing lives. In ‘The Deadly Attachment’ the hapless Walmington-on-Sea platoon is left in charge of a group of German prisoners of war. Determined to maintain authority and conscious of giving away sensitive information to the enemy, Mainwaring gives us the most famous Dad’s Army quote ever; “Your name vill also go on ze list! Vot is it?” says a German prisoner. To which Mainwaring blurts out “Don't tell him, Pike!”