This Country is such a delicate, fragile thing that I always have the image of its sibling writers and stars, Daisy May and Charlie Cooper, cradling a baby bird. I find myself holding my breath at the start of every series, afraid that this time a hand will slip and crush it, or that their careful nurturing will take a wrong turn and their charge will fail to fledge and take wing.

I have breathed a sigh of relief twice now, and I exhaled again as the third and final series of the BBC mockumentary about Cotswolds village residents Kerry Mucklowe and her cousin Kurtan began. How they do it, I don’t know – any more than you could say how Stephen Merchant and Ricky Gervais did it in the glory days of The Office, or Rufus Jones does it now with the hilarious, heartbreaking Home. But they pad as sure-footed in Adidas trainers as ever, along the lines separating hope from despair, portraiture from caricature, punching up from punching down, comedy from tragedy and a thousand other subtle divisions besides.

This time they have an extra obstacle to navigate in the opening episode – accounting for the real-life death from heart failure at the age of 33 of the Coopers’ friend Michael Sleggs, who played the Mucklowe’s vaguely unrewarding friend Slugs. The Rev Francis (Paul Chahidi, continuing his fine work in playing a decent man holding back the tides of despair with an optimism that is rarely replenished by his parishioners) breaks the news to viewers, but it is left to Kerry and Kurtan to fill in the details. Slugs had persuaded them to take part in a zombie escape room adventure in Swindon on the Saturday, “but unfortunately he passed away on the Friday,” says Kerry. “Which was sort of a relief in a way,” adds Kurtan, who is ever too sweet and solipsistic to deceive. “Bless ’im.”

But for every ending there is a new beginning. Kerry has just started a job at the local dump. “Due to unforeseen financial circumstances, work has been forced upon me.” She owes Kurtan the £500 his nan gave him to invest in Bitcoin. She bought an alpaca to enable her to set up her own pillow-stuffing business but it turned out to be “physically my largest mistake”. Kurtan is looking after Kerry’s house and her mum while she is out. He is a conscientious lad: “Do you want turning, Sue?” he shouts. “Yes please,” comes the smoke-ravaged voice from above. “The snow shovel’s under the stairs.” All the details of This Country could so nearly be true. It is one of its most exquisite facets.

Kerry and Kurtan suffer one of their frequent fallings out when yet another of Kerry’s historical misdemeanours is unearthed, ceaselessly as ever creating for themselves the drama that life fails to provide. The vicar tries to counsel forgiveness. “I can’t move on till I’ve seeked revenge, unfortunately,” Kurtan explains, with his signature endearing regret. “At the end of the day, I’m a very vindictive person. It’s what makes me me.” He avenges himself, Kerry accepts it and once again you find your eyes filling during the final scenes because, while you were laughing, they snuck in and crowbarred your heart apart.

In later episodes, Kerry’s father – in all his ordinary monstrosity – reappears and puts her (so shielded by her limitations in some ways, made so agonisingly vulnerable by them in others) through the wringer once more. Kurtan gets his provisional licence and plans to drive to a sushi restaurant in Cheltenham – until he sees Kerry’s face. Mandy still wanders the village in casually terrifying fashion, and random animosities continue to add spice to life. My favourite is Kurtan’s profound and never-explained animus towards a woman called June and her magnificent garden. “The sheer arrogance of it! Makes my blood boil.” There is also a love interest for our boy, in the shape of Slugs’ former girlfriend Kayleigh. Kerry points out his attraction to the vicar. “He’s standing side on to her to hide his birthmark,” she explains. “Says it’s the one thing that lets him down.”

All of human life is here, in this bleak, hugely funny, intimate, seemingly slight yet ridiculously potent series of six perfectly formed half-hours. This last series finds welcome opportunities to deepen characters – particularly the vicar – and illuminate broader social issues and sadnesses. It continues to bring the Mucklowes so vividly to life that it always takes a moment for me to come back to reality when the credits roll. The baby bird takes glorious wing and soars.