Devotees of the popular American sitcom Friends are known, I believe, to converse about which member of the cast they most resemble – “OMG, I am sooo Phoebe!”, “you’re such a Chandler”, and so on. I have spent the last three and a bit decades doing something similar, but with the characters of Dad’s Army, the British sitcom first broadcast in 1968, which ran for 80 episodes until 1977, and was recently subjected to an ill-advised cinematic remake. It was a staple of my television viewing as a child, and I eagerly anticipated sitting down on a Saturday teatime for that animated opening sequence (see above) in which Nazi swastika arrows loop through continental Europe, pushing back the Union Flag arrow until it retreats across the English Channel, and sits there, jabbing towards conquered France like an impotently yapping dog. I often see Dad’s Army dismissed as Keep Calm & Carry on war-nostalgia TV, hardly surprising when it was sucked into the right wing media's rhetoric around Brexit, but it never has been for me. Instead it was, and is, a work of art simmering with a sense of dread – those swastika arrows moving across the map in the opening credits give me the creeps.

That animation is accompanied by one of the greatest telly themes of all time, which, though it sounds like it could be one, isn’t a wartime era song at all, but was composed for the programme by Jimmy Perry and Derek Taverner, and sung by music hall entertainer Bud Flanagan. “Who do you think you are kidding, Mr Hitler?” it asks the perfidious Führer over the sea, promising that should the dreaded German parachutists descend from their Ju 52s,

“Mr Brown goes off to town on the 8:21
But he comes home each evening and he’s ready with his gun.”

Against the upstart Mr Hitler and his airborne troops, possibly or probably dressed as nuns, is the array of yeoman Englishmen in the Walmington-on-Sea Home Guard platoon: the butcher (Corporal Jones), the bank staff (Captain Mainwaring, Sergeant Wilson, Private Pike), the undertaker (Private Frazer) and the old man (Private Godfrey). Although I spent my childhood eagerly hunting through the Radio Times for Sunday afternoon war films – The Dam Busters, 633 Squadron, The Guns of Navarone – watching Dad’s Army was a very different experience. The characters in the classic films were unattainable, fantasy objects, idealised versions of men whose actual lives had been distilled to fit the requirements of a couple of hours of celluloid and a public demand for narratives of heroism against the odds. Dad’s Army, though, wasn’t like that. Even though by the time I was watching the programme in the 1980s and early 90s barely any of the main cast members were still alive, I had a sense of connection with them. They were decidedly unheroic, but in that, they were beautifully ordinary and familiar. These were men who looked the same age as the Second World War veterans I saw on TV or knew at church – it was always strange to me to think that the men who fought in the war were actually young.

Despite the music-hall haplessness of the Home Guard as depicted in Dad’s Army, Britain’s defence units were a deadly serious business during the war years. The force was founded in May 1940 as the Local Defence Volunteers to counter the threat of a German invasion and social unrest at home. Open to men aged between 17 and 65, by July that year it had attracted over 1.5 million volunteers, often armed with little more than farm tools or old shotguns. At first, the uniform was just an LDV armband. The formation was soon renamed the Home Guard, and eventually units were properly armed with rifles, Sten submachine guns and some heavier armaments. There were even small detachments, known as Auxiliary Units, who had hideouts stuffed with weapons hidden in the countryside. Were an invasion to happen, their duty was to disrupt German activity until they were eliminated, including by assassinating local officials and bigwigs likely to collaborate with the occupying forces. We can never know whether the Home Guard would have put up an effective resistance to invasion, yet they remain as an essential part of our national mythos from 1940 – an ill-equipped yet plucky and characterful redoubt against the might of Nazi totalitarianism.

As such, Walmington-On-Sea stands as a cipher for England. It’s a sort of everywhere-and-anywhere place, a town defined by its staple institutions of bank, butcher, church and blown-up pier. In Walmington, life tries to go on as it did during the peace. The church windows have blast tape on them, Jones the butcher might slip an extra sausage into your packet in defiance of the ration and everyone carries a gas mask in a cardboard box, but by and large the town carries on as perhaps it might have done before, when the bank staff didn’t replace their bowler hats for forage caps at the end of the working day. The small-town Englishness of Dad’s Army is not an identity that shows any sign of dissipating more than 50 years after the series was first broadcast, and more than 80 years beyond the period in which it was set.

Captain Mainwaring, played by Arthur Lowe, is utterly familiar today. He might be the embodiment of middle-class Edwardian hubris and petty resentment, but it worries me that, even though audiences in the 60s and 70s were able to recognise the harrumphing, self-important patriot as a pompous fool, we seem to have plenty of his ilk in society today, most visibly the type found going purple in the face in the audience of Question Time. Mainwaring is there to mock that archetype, not, as some who dismiss the programme as dodgy nostalgia would have it, to celebrate it. Nevertheless, he’s also a gloriously nuanced character, notably in an oddly moving episode in which his alcoholic brother (played magnificently by Lowe himself) appears in Walmington-on-Sea to reclaim a family heirloom that he believes by rights to be his. When it comes to the Friends-esque relatability game, I see myself in Mainwaring, just as I have my Accidental Partridge moments. I certainly related to Private Pike, the somewhat floppy young man whose mother was always convinced he’d be able to dodge the call-up due to his constant ill health. Frazer, the dour Scottish undertaker who constantly proclaimed that the platoon was “doomed”, with wide eyes bulging from his craggy face, seemed to reflect my own melancholic nature. And then there was Wilson, played by John Le Mesurier: the slightly raffish, inept, diffident sergeant on whom I’ve always had something of a crush. The programme also acknowledged the complexities of wartime masculinity, with the shirker and spiv Private Walker still a sympathetic character despite his cowardice.

Corporal Jones, the sensitive old buffer who’d fought in Britain’s colonial wars and provided, in “They don’t like it up ‘em!”, one of the most memorable catchphrases of British comedy, was not merely some old fossil. After all, many of us had grown up with the actor Clive Dunn’s strange pop hit ‘Grandad’. Jones’s inability to keep time with the rest of the platoon, his foot stamping down a split second later than everyone else when called to attention, was an antidote to the jack-booted, high-kick marching of the German soldiers on newsreels. Unlike the veterans of the recent Second World War, Jones never shied away from droning on about his exploits in the army. Appearing in character on a 1988 episode of the chat show Wogan, 'Jones' said: “I didn’t tell you about when I was in north Africa did I? Have you got an hour or two?” Despite this, his character never glorifies military service. When Private Pike gets his call-up papers in the episode 'When You’ve Got To Go', the old-timer gives him some advice: “One thing won’t have changed and that’s the comradeship. If someone nicks your kit, you make sure you nick somebody else’s. Never volunteer and always look after number one. If someone drops you in it, make sure you drop them in it. It’s the best part of the army, comradeship.” Jones’s character works because he is a buffoon stuck in some imagined glorious past, but also deeply sensitive. There was something gentle about the slightly camp medic Godfrey, too – and it was he who was at the centre of the episode that is Dad’s Army’s finest hour.

‘Branded’ was broadcast in November 1969, the first episode in colour, and timed to coincide with that year’s Remembrance commemorations. The idea of the platoon doing any kind of combat is darkly farcical. Even more so is the notion that this ragtag bunch of men might be capable of close-quarters fighting, giving an invading German force what Corporal Jones loved to call “the cold steel”. ‘Branded’ opens with the platoon practising creeping up on a sentry to despatch him with a bayonet in the guts or across the throat. It transpires that after catching a mouse, Godfrey has had a moral crisis – if he couldn’t kill a mouse, how could he kill a German? He admits that he joined the Home Guard without realising it was a combat unit, and reveals that in the First World War he had been a conscientious objector. The blimpish Mainwaring is livid. “I am old-fashioned. I can’t stand cranks. Can you imagine a man not wanting to fight? It isn’t normal.” Godfrey leaves the platoon, which unsettles the men. Jones misses his tea. Mrs Pike is overheard telling Wilson that “men ought to be men”. Frazer says “it’s a disgrace” that they had a “conchie” in their ranks. On an exercise, the men have to enter a shed full of smoke to practice a rescue. Before he goes in, Mainwaring tells Godfrey that he “wants none of your conchie tricks”. When the older man emerges, the Captain is nowhere to be seen; Godfrey crawls back into the room and rescues him, saving Mainwaring's life at great risk to his own.

The platoon crowd into Godfrey’s non-more-Edwardian bedroom (single brass bedstead, patterned wallpaper) where Jones presents him with a package of sweetbreads, and Frazer gives him a bottle of Scotch. Wilson asks Mainwaring if he’s not going to thank Godfrey for saving his life. Mainwaring is about to launch into a valedictory speech, but sees above the bedhead a photograph of Godfrey not only wearing a military uniform, but also the Military Medal. “But you told us you were a damn... that you were a conscientious objector, stammers Mainwaring, perplexed. “How did you win the medal?” It transpires that Godfrey joined the ambulance corps and, during the Battle of the Somme, went out into no man's land and saved several lives.

Most of the cast of Dad’s Army had served during the Second World War, and a couple in the First too. ‘Branded’ becomes even more poignant when you know that Arnold Ridley, the actor who played Godfrey, was seriously wounded in close-quarters fighting at the Somme in 1916. Among his wounds was a jab from a German bayonet – for Ridley, the “cold steel” so often summoned by Corporal Jones was no laughing matter. In the Second World War, Ridley was part of the British Expeditionary Force evacuated from Boulogne, and after being discharged from the army, he joined his local Home Guard. Speaking about the ‘Branded’ episode, Ridley reflected on his own service in the First World War, saying that “it’s good to mention 'conchies', as they were called, because they went through hell a lot of them, and a lot of them had high principles. I'm very honoured to play it." Ridley wasn’t the only cast member to have served. John Laurie, who played Frazer, also fought in the First World War, Clive Dunn was a POW in the Second, Arthur Lowe an army engineer in the Middle East, and so on.

To modern audiences, Dad’s Army might seem dated, but I don’t get a whiff of bunting from it, because the writers, cast and crew were all people who were aware of the privations and difficulties of military service. The platoon of Walmington-on-Sea's Home Guard are not just playing at soldiers – for all Mainwaring’s pomposity, they are determined to fight should the church bells start ringing in alarm, signalling an invasion.

Dad’s Army also seems to hide a deeper truth, one that winks at us in the title. Although they are a “Dad’s Army” of a certain age, the main characters of the Walmington-on-Sea platoon don’t appear to have any sons to worry about, far from home and facing violence. There was a slipperiness between the Saturday night telly series and the reality of these men in their normal, ageing lives that meant I saw one as the other. Dad’s Army were the Home Guard but, curiously, seemed to stand for the wartime generation of soldiers too. And as poor as the martial skills of the platoon were supposed to be, the ominous feeling I always used to get from the programme came with the question "what if?" – what if the jobsworth church warden had had to rouse “his reverence” the vicar in the dead of night to ring the bells that would have heralded an invasion? It’s only in recent years that historical research has suggested that a German invasion of Britain in 1940 was extremely unlikely to be attempted, or to succeed. Postwar generations, including my own, very much grew up on the idea that, in 1940, Home Guard detachments like the one depicted in Dad’s Army could have ended up on the frontline. Watching the programme I always imagined, and still do, Stuka dive-bombers screaming down on the Novelty Rock Emporium, shells from German warships such as the Scharnhorst and Gneisenau exploding on the promenade and pier, and crack units of the Fallschirmjäger of Nazi iconography dropping from Ju 52 transports over the nearby countryside, until Mainwaring, Jones, Wilson, Pike, Frazer, Walker and Godfrey all lay dead, their blood flowing in the well-kept municipal gutters of Walmington-on-Sea.