‘If I’m ever asked to explain that movement, I always call it The Alienated Synthesists. We were all going round in long coats from second-hand shops, saying how terrible things were. With a synth.” That’s the splendid Phil Oakey speaking, with a grin, as he looks back to the late 1970s, when The Human League didn’t write songs with “baby” in the chorus and didn’t have the two girls, Joanne and Susanne, singing back-up and dancing like they were at a sixth year disco. Instead, back then, the League were serious young men dressed in serious shades of grey, chanting about dehumanisation. (“Dehumanisation is a very big word/ It’s been around since Richard The Third,” ran the unforgettable couplet on their early song, Blind Youth. Although it should be noted that, unlike the lyrics of many of their peers, it was actually supposed to be funny.)

A consideration of these Alienated Synthesists and the inspiringly bleak late-1970s/ early-1980s environment that produced them – such brilliant, awkward, nagging and usually northern post-punk outfits as Cabaret Voltaire, Throbbing Gristle and Joy Division, as well as slightly less estranged acts like John Foxx, OMD and Gary Numan – makes up the first half of Synth Britannia (BBC Four, Friday, 9pm), the latest in BBC Four’s unfailingly solid series of documentaries on the cultural impact of British music. The second half lays out what happened next: as the strange sounds those groups pioneered in their personal radiophonic workshops were gradually digested by the mainstream, to finally come out the other end as shiny 1980s pop.

The earlier industrialist bands were concerned with creating distressed concrete anomie soundtracks to show off how many JG Ballard paperbacks they’d read, but Basildon boys Depeche Mode’s first

electropopping singles were more concerned with getting girls dancing round their handbags. Meanwhile, where first-wave synth groups sought an emotionless, or at any rate neurotic vocal delivery, later synth-and-a-singer duos like the deliciously deviant Soft Cell and Yazoo added the blood and fire of a soulful voice to the icy electronics, laying down a blueprint for club anthems to come.

Featuring interviews with all these key players, and Midge Ure, the film charts this process coherently and convincingly. It’s the opening section that’s most absorbing, though. Surrounded by landscapes that resembled Quatermass sets, fired up by Ballard’s clinical sci-fi parables on the deranging effects of modern living and William Burroughs’s just-because-I’m-paranoid-doesn’t-mean-they’re-not-out-to-get-me fantasias about surveillance culture, this was perhaps the last generation of young groups to be actively apprehensive about technology and tomorrow (1984 loomed heavy), even as they schizophrenically embraced it.

These groups were also, possibly, among the last to actually understand that technology, down to its core. As well as continuing the Music Britannia strand, the documentary is part of the Electric Revolution season on the evolution of gadgetry in recent decades, and the relationship between the musicians and their equipment itself is fascinating.

All these bands drew inspiration from punk, but while punk’s DIY aspect is one of the most overused clichés in music writing, here it was exactly the case. It’s not just that many of these people turned to synthesizers because they found them easier to play than guitars (“Guitars really hurt your hand,” Oakey shudders). In many instances, they actually built their instruments from scratch, powering them with fat blue Ever Ready batteries. Joy Division/New Order man Bernard Sumner recounts months spent painstakingly soldering together parts bought mail order, trying to follow circuit diagrams in Electronics Today magazine to assemble his first synthesizer.

You can hear it in the music, that smudgy trace of burnt fingers on wires, the crackle of dodgy circuits overheating, metal screwed to wood. The retro-futurism sparks a weird nostalgia: those gnarly, stubborn machines, chunky synthesizers that resembled the control panels of nuclear reactors, are pieces of the tomorrow that never came, because sleek anaesthetic seductions like iPods, Rock Band and Facebook came instead. Like HAL in 2001, the unpredictable, temperamental nature of those old machines becomes a recurring theme.

Here’s Oakey again, on a 1977-era Korg 700S synth: “Fantastic machine, totally eccentric… You can’t tell why it’s doing what it does, but it sounds great.”

The documentary is by no means perfect. The first sighting of Kraftwerk in Britain (courtesy of Tomorrow’s World in 1975 – another argument for the licence fee) is given due place as the synthesizer groups’ Big Bang, but the place of David Bowie’s “Berlin Trilogy” goes unmentioned. There are other omissions that, while they may not glare, still hurt (surely, The Associates warranted at least a mention). From a musicological point of view, the film also fumbles badly toward the end: in a sudden rush to tie things up, it’s as if the director, Ben Whalley, remembered he’d forgotten New Order’s seismic Blue Monday and frantically sticks it in, nonsensically, after The Pet Shop Boys.

But so much of what is here is on the money. Whalley, in fact, is probably due a medal. He’s been behind a whole string of fine BBC Four Friday-night music documentaries, including Detroit: From Motown To The Stooges, Folk America, If It Ain’t Stiff and Once Upon A Time In New York.

Next week, same channel, same time, he’s back with another, even better film, Krautrock: The Rebirth Of Germany, exploring the surge of uncompromising groups that emerged in the country in the late-1960s, and interviewing all of them: Amon Duul, Popol Vuh, Tangerine Dream, Cluster, Can, Faust, Neu!, Harmonia, and, of course, Kraftwerk.

Clocking in at an hour, it leaves you wanting more, but it covers a lot of ground. Sadly, Kraftwerk’s main menmachines, Ralf Hutter and the recently departed Florian Schneider, are absent, but former member Wolfgang Flur shows up. And so, as a bonus, does Iggy Pop, recalling the time he went shopping for asparagus with Schneider, and talking brilliantly about Neu!’s music.

Featuring many bands who would influence Britain’s keyboard-slinging post-punks, and briefly covering Bowie’s magpie period in Berlin, the Krautrock film acts as a prequel to Synth Britannia. But it also leaves the British acts looking a little embarrassed and weak. The German bands came of age at a time of great unrest, as their nation struggled with the guilt and anger of its past. The music grew against the backdrop of communes, radical politics and riots in the streets. The members of Amon Duul knew the Baader-Meinhoff gang before they were the Baader-Meinhoff gang.

The music these groups made was diverse, but they all shared one aspect, which Whalley brings to the fore. These were all children of parents of the Nazi era. Living in their divided country, they didn’t want to draw on English and American rock music, and they didn’t want to revisit German history. So they turned towards electronic music as something untainted by the past, a throbbing, droning, endless Year Zero of their own. A decade later in Britain, young men in raincoats started plugging in because they wanted to.

What gives the German music its particular edge is that it’s the sound of people playing it because they had no other choice.