WHEN two savvy Southerners hooked up with two West Midlands wild men, it was a case of light the blue touch paper and stand well back. As legend has it, they were supposed to go down like “a lead balloon”. But, in 1968, they formed the most explosive and arguably most successful band in rock ’n’ roll history — Led Zeppelin. Representing the suburbs of London were Jimmy Page (guitars) and John Paul Jones (bass and keyboards).

From the outskirts of Birmingham came Robert Plant (vocals and harmonica) and John “Bonzo” Bonham (drums). When the four played together, it was — as their incendiary Immigrant Song implied — like hearing the “hammer of the gods”. By incorporating grinding blues, sultry R&B and delicate folk music into their sound, they offered so much more than the “hard rock” and “heavy metal” labels they came to be saddled with.

Plant once told me: “In the middle of all our madness, we had a Zeppelin style. You could feel it and you could hear it.”. Next week sees the arrival in UK cinemas of the first band-authorised film about their roots, their formation and their meteoric rise, Becoming Led Zeppelin. The two-hour documentary was written, directed and meticulously researched by Bernard MacMahon in tandem with screenwriter and producer Allison McGourty.

The pair had previously masterminded the mammoth, acclaimed American Epic project, exploring the impact of pioneering 1920s recordings by the likes of Mississippi John Hurt, The Carter Family and Lead Belly through film, soundtracks and a book. In Becoming Led Zeppelin, MacMahon and McGourty trace the musical journey of each band member from their childhoods in post-war Britain . . . cue for cute family album snaps.

They paint a detailed picture of four characters with contrasting personalities who were ALL music obsessives from an early age. They provide a blizzard of ­footage of the band’s influences — Sonny Boy Williamson, Little Richard, James Brown and two fired-up acts from this side of the Atlantic, Lonnie Donegan and Johnny Kidd & The Pirates. We see Page and Jones becoming ace session men while startl­ingly young. Both backed Shirley Bassey on her immortal 1964 Bond theme Goldfinger, for instance.

We witness Plant and Bonham, buddies as teenagers, plough their way through a tangle of bands in the West Midlands with no money and a “whole lotta” passion. Yeah, we were very lucky, for a period of time, Jimmy and I were made for each other. To cap it all, the four musicians collide, the sparks fly and they become world beaters — fast. The film serves as a mesmerising collage of loud, unvarnished live performance, telling insights from Page, Plant and Jones as well as evocative archive audio from the late Bonham.

The release of Becoming Led Zeppelin, after years in the works, inspired me to revisit interviews I conducted for expanded editions of the band’s back catalogue — eight studio albums released between 1969 and 1979 and their 1982 compilation, Coda. In the first of four illuminating encounters with Page, I remember joining him beside a roaring log fire at a swish boutique hotel, just round the corner from London’s Royal Albert Hall.

By then, with his swept-back white hair, the six and 12-string maestro — the “Pontiff Of Power Riffing” if you will — bore the air of rock royalty. Over coffee, he talked with immense pride and encyclopaedic knowledge about the formation of the band, the glory years and its untimely demise following the death of Bonham in 1980. Ninety minutes later, in stark contrast, I found myself sitting at a scrubbed pine table, having a pint with Plant in an upstairs room at his Primrose Hill local.

With his shaggy mane and easy manner, the singer with the spectacular holler roamed freely between Led Zep, his latest solo album and his beloved football team, Wolverhampton Wanderers. His first words to me were, “Have you done Jim Bob?” followed by a mischievous, “Laugh a minute?”. Let’s just say that Page, who wrote most of the music, and Plant, who wrote most of the lyrics, are like chalk and cheese, the former an earnest soul, the latter a freewheeling spirit.

It’s well known that they haven’t always seen eye to eye but there can be no doubting their intuitive Led Zeppelin relationship which, of course, ties them for ever. “Yeah, we were very lucky,” admitted Plant. “For a period of time, Jimmy and I were made for each other.”. Every musician dreams to be in a group like Led Zeppelin and I was really fortunate to have been a founder member. Then he added: “But it was also the four of us. Each of us slipped into a role where self-expression was never marred. There was always a free passage to take an idea to the extreme.