Crook plays Andy. Toby Jones is Lance. In 2014, in the very first episode, we were introduced to the pair detecting in a ploughed field. Andy had found “Three shotgun caps and a Blakey”. Lance pulled something out of the ground. “What you got?” asked Andy. Inspecting his find through a magnifying glass, Lance replied: “Ring pull. ’83. Tizer.” Metal detecting is not all Roman gold and Saxon hoards. In fact, it very rarely is.

Why do they do it? “Metal detecting is the closest you’ll get to time travel,” Lance explains. “See, archaeologists, they gather up the facts, piece the jigsaw together, work out how we lived. We unearth the scattered memories, mine for stories, fill in the personality. Detectorists – we’re time travellers.” The show charts the pedantic pair’s finds and their minor domestic dramas. It is defiantly low-stakes, cheerfully bucking every TV trend. In a world of expansive, expensive epics, it’s a priceless miniature. It’s not about questions of life and death or the fate of humanity. There are few problems that can’t be solved over a pint in the Two Brewers or a cup of tea during a break in the corner of the field. (“Tea without sugar is just vegetable soup,” insists Lance). What’s at stake is whether Lance’s daughter will ding his treasured yellow Triumph TR7 if he allows her to drive it, or whether Andy’s wife Becky will be annoyed when she discovers he’s packed in the job he hates. Or Andy and Lance’s friendship, which is what the show is really about.

It’s often described as a “gentle” comedy but there are plenty of laugh-out-loud moments. Some of the funniest come during the pair’s run-ins with a rival metal detecting duo who have a very cavalier attitude to the detectorists’ code, and who are always changing their name. They’ve been the Antiquisearchers, the Dirt Sharks and Terra Firma. Lance and Andy have dubbed them Simon and Garfunkel, although they’re actually called Phil Peters (Simon Farnaby) and Paul Lee (Paul Casar) – Peters and Lee, get it? There’s a running gag in which they are introduced with the opening bars of Sound of Silence, and Andy smuggles a Simon and Garfunkel lyric into the conversation, which usually ends in infantile insults being exchanged.

Set in Essex but filmed in Suffolk, Detectorists feels quintessentially British, and is packed with British cultural references. How many non-UK viewers understand, say, the conversation about the accepted protocol when correctly answering a starter for 10 on University Challenge? (“What you want,” says Lance, “is a humble smile and a nod to your teammates as if to say ‘I know you guys knew that one too’.” “That’s it. Spot on,” agrees Andy). Yet the show has a dedicated and growing following outside Britain.

Do they know what a “chinny reckon” is in Tel Aviv? Seems unlikely, but an Israeli newspaper called Detectorists “buried treasure”. Are they familiar with Fiona Bruce in Bordeaux? Possibly not, but a French paper described Detectorists as “délicieuse” and “un baume apaisant“ – a soothing balm. In an online discussion, a fan from India wrote “this is not a TV show, it’s soul food”. A viewer in North Carolina poetically described it as “a deep, grassy field in an asphalt world”. In appreciation of the show’s pastoral elements, the LA Times said it was “almost Shakespearean” and compared it to A Midsummer Night’s Dream. Toby Jones, after the Baftas ceremony where the series won an award, told the story of cycling through New Orleans when two guys rushed out of a bar to tell him “Man, we love the Detectorists!”

‘About hobbyists, for hobbyists’

Crook appears genuinely embarrassed when this global adulation is mentioned, and says he can’t explain it. “Toby is able to wax lyrical more than me about those sorts of things,” he tells BBC Culture. “It was always my idea to write an uncynical comedy about hobbyists for hobbyists – people with obsessions – and I guess those sorts of people are all over the world, and they’re not often championed so perhaps they can relate to it.” Jones, incidentally, is quite clear on why it is so universally loved. “It’s a brilliant, brilliant piece of writing,” he says.

Ben Lindbergh is a senior editor at The Ringer, a Los-Angeles-based pop culture and sport website and podcast network, and has written about the show.

“I imagine most Americans who appreciate Detectorists like it for the same reasons British fans do,” he tells BBC Culture. “It’s just a well-written, well-acted, keenly observed show, and its theme of trying to find one’s place and purpose in life is universal.

“It is very British in some respects, and perhaps it helps to be a bit of an Anglophile, but I didn’t find any of the references or settings exclusionary or alienating. The specificity of the show is what makes it for me: it fondly and respectfully captures a niche subculture that I otherwise wouldn’t know much about, and the fact that it’s set far from my native New York City – in a distant, slow-paced land of pubs and rolling hills and quiz shows – only enhances the sense that I get when I watch it of escape and immersion and spending some time in a different world. My wife and I took a trip to Cornwall a few years ago, and we were excited when we turned on the TV and saw University Challenge.”

The show is filled with surprising little Easter eggs. For example, how many viewers missed the fact that – spoiler alert – the first season ends with an aerial shot of Lance and Andy walking away, completely oblivious to the faint outline in the grass of a buried Saxon ship? Who could have predicted, in the final episode of the third season, a supremely silly homage to the barn-building scene in 1985 Harrison Ford film Witness?

And there are exquisite, understated moments of joy and sadness. Watch the scene in the second season in which Terry’s wife Sheila (Sophie Thompson) – a woman with a very literal interpretation of the adage that when life gives you lemons, you make lemonade – is sympathising with Lance over his difficulties with his daughter. Thompson’s brilliant performance makes plain that Sheila has known devastating loss, although it is never specifically mentioned and we never know what it is. “It is my favourite scene in all that I’ve done,” says Crook. The fact that Sheila is usually such a comedic character makes it all the more poignant and piercing.

There, in the background of another scene – blink and you’ll miss it – is Varde on one knee, proposing to Louise with a ring she’s just found. You can actually buy Louise and Varde tote bags, T-shirts, duvet covers. You can buy DMDC (Danebury Metal Detecting Club) T-shirts, T-shirts bearing a Detectorists’ guide to ring-pulls. There is even a fanzine Waiting For You, named after a lyric from the haunting theme song by Johnny Flynn. There have been three issues so far and a fourth is due.

Waiting For You is edited by Cormac Pentecost, a self-employed publisher from Shrewsbury. “I was very late in discovering Detectorists because at the time it was broadcast I wasn’t really watching TV but I kept seeing posts on the Folk Horror Revival Facebook group about how some of the episodes had eerie, ghost-story elements, and that prompted me to give it a watch,” Pentecost says.

Mystical elements

“On a first viewing, it’s the comedy and the generosity of the characterisation that appeals but there’s something about it that draws you back for repeated viewings. Partly it’s the landscape photography, partly the sense of solitude and quiet that it radiates – unusual things for a sitcom. More deeply, as we watch Andy and Lance searching for treasure, we can sense that these minimum-wage workers, who by many measures might be judged to be losers, are in touch with something sublime in the English landscape. Almost by accident, they have discovered a spiritual side to life.”

The beautiful landscape is certainly a key part of Detectorists. Crook also likes to include shots of the local flora and fauna in every episode – insects, birds, deer and so on. But watching Lance and Andy slowly drift across a field, gently wafting their detectors from side to side is like watching a pair of meek and mild ruminants wandering over a pasture. They are as much a part of the landscape as all the other creatures that inhabit it.

Also, the show has leaned more into the brushes with the supernatural as it has gone on. On a few occasions, including in the new feature-length episode, the past seems to bleed into the present, and some sort of unseen hand seems to be guiding Lance and Andy.

“I don’t believe in the supernatural but I’ve been fascinated by it ever since I was a kid,” says Crook. “I got The Unexplained magazine – about ghosts, poltergeists, spontaneous human combustion, whatever – and I loved it. I guess my fascination with it comes out in my scripts. When I did Worzel Gummidge [that Crook also writes, directs and stars in] it was an opportunity to explore those mystical elements and themes in a far more obvious way but, yes, there are a few things going on in this.”

Crook is an occasional detectorist himself and his creation has the approval of the detectorist community. Julian Evan-Hart is the editor of Treasure Hunting, a monthly magazine for detectorists. “It is an amazing series, and it is obvious that it is written by a detectorist because there are little jokes in there which, in inverted commas, a ‘normal person’ probably wouldn’t pick up on,” he says. “The show has just become part of metal detecting culture now. I get articles for the magazine quoting it, and we all know a Lance or a Terry.”