On the musical level he certainly succeeded. Imagine is the best-loved album of his solo career, while its title track is perhaps his most revered. By contrast to its austere predecessor the new music had melodies in abundance, and colour and variety. It had flashes of broad humour and moments of absolute joy.

In his home outside London, at Tittenhurst Park in Ascot, John had built a studio where he could record the raw tracks, without recourse to his traditional base at Abbey Road.

The producer Phil Spector returned to help John oversee an informal family of musicians.

Among them were George Harrison, and friends like Klaus Voormann and the drummer Alan White, who had all played on John’s tremendous debut collaboration with Spector, ‘Instant Karma! (We All Shine On)’.

The Rolling Stones’ favourite pianist Nicky Hopkins was there, and members of the Apple label’s Badfinger.

As Yoko says: ‘It was so good to have breakfast in our own home and walk right into the new studio next to it. We could smell the grass and the trees from the garden and heard the birds chirping. We felt like they were helping us.’

Imagine took shape in the early summer, after which the tapes were taken to New York for final overdubs (not least the magisterial saxophone of King Curtis) at Record Plant East.

It seems that everyone involved, and certainly John himself, had a sense of its being exceptional. Here were songs that threw revealing light on his whole personality at that point – from the devout but imperfect lover to the embattled former Beatle; a man preoccupied by his inner doubts yet ready for anyone when his righteous fury was aroused.

The keynote song itself was drawn from Yoko’s work. It was so influential upon John that he later said she deserved a co-credit.

As far back as 1964, in her collection of poems called Grapefruit, Yoko began each piece with an invocation to ‘imagine’: one example, from 1963’s Cloud Piece, is quoted on the album cover. Whether in spiritual or earthly matters, the idea runs, we must visualise our goals before we can achieve them.

‘imagine the clouds dripping. dig a hole in your garden to put them in.’

yoko ’63

It’s a theme to which Lennon returned frequently, and the hymn-like simplicity of its setting reflects his basic faith – namely, that our collective imaginations are a force for good.

The cover art, from a photograph by Yoko, further shows John in a dreamer’s role, literally with “head in the clouds.”

But typically of Lennon there was an earthier touch, as well, in a giveaway postcard of him wrestling a pig – satirising, as most fans at the time would have spotted – Paul McCartney’s pastoral image on his own solo LP of that year, Ram.

For all that Imagine has a generosity of spirit, the infamous ‘How Do You Sleep?’ is narrow and hard, despite its lush and spacious arrangement.

John would later say that the attack on his former musical partner was, in fact, as much an assault upon himself.

‘Gimme Some Truth’ looks out with an idealist’s impatience to the political world, while ‘Crippled Inside’ has that quality (more obviously than ‘How Do You Sleep?’) of a tirade that is leavened with self-reproach. Its knockabout honky-tonk contrasts with Lennon’s previous album, John Lennon/Plastic Ono Band, through the lyric shares a “primal scream” acuteness.

Likewise ‘Jealous Guy’, another unflinching look into the writer’s own sense of failure, is spun into a different realm by its ethereal melody. If John felt that his last album – forbiddingly stark to some ears – had not found the mass audience its songs deserved, he was not about to make the same mistake with Imagine.

Emotional range is central to this record’s enduring appeal, with light and shade at every turn. From tough, grinding rockers like ‘It’s So Hard’ and ‘I Don’t Wanna Be A Soldier Mama I Don’t Want To Die’ we are sent to the solace of ‘Oh My Love’ or the confessional vulnerability of ‘How?’.

And the album skips away in a song of sheer delight, ‘Oh Yoko!’, possibly the happiest thing that John Lennon ever committed to record.

On its release in September 1971, the Imagine album was recognised as a rounded self-portrait of this complex, candid, passionate man. It re-established his eminence in the commercial firmament, among a rising generation of rock’n’roll stars such as Led Zeppelin and David Bowie. It was clear the 1970’s John Lennon would not sit in the shadow of his 1960’s self.

When he left England for America, on 3 September 1971, it was just another trip in John’s turbulent existence, probably in search of some fresh cause to champion, more battles to fight and unknown songs to sing. Nobody knew, of course, that he would never see his homeland again.

For now, New York looked like the city to be – the capital of the world, as he believed – where new adventures beckoned with siren allure…

Written by Paul DuNoyer
Included in the CD booklet of EMI’s 2010 Lennon 70 Definitive Remaster of Imagine.
Read Paul’s book: Working Class Hero: The Stories Behind Every John Lennon Song.