The path down Memory Lane is a road much travelled, especially for music fans who remember the time when the world was a very different place, seen through the eyes of a young idealistic and very independent teenager. How those years seemed to melt away at Under The Bridge in London when the 45 years dividing 1970 and 2015 melded seamlessly together to the point where there was even a distinct whiff of patchouli oil in the air.

The venue is an unexpectedly spacious and welcoming music space, nestling under the east stand of that soccer shrine, Stamford Bridge, in west London. It’s a place a fellow gig-goer remarked was somewhere you went to on purpose rather than called in out of a passing, casual interest.

There were around 200 devotees assembled on Friday 4 September to hear Air Conditioning in its entirety, which, when first released in 1970, was recognised as being one of the early albums that defined the progressive rock genre and, for record collectors, the first ever “modern rock” picture disc.  Its creators, Curved Air, were also ground-breaking, consisting of a group of virtuoso musicians who fused classical leanings with folk, art house and electronica.

Fronted by prog’s original pin-up girl, Sonja Kristina, the years simply melted away at that faraway place in west London.

Looking at all those assembled and imagining everyone 45 years ago, you could picture the Afghan coats, cheesecloth shirts, flared jeans and long straggly hair, then the hallmark of youth rebellion.

Just the two original members of the band remain:  first and foremost, the flamed-haired Sonja, ever the enchantress, always the focus of attention with her smoky voice and sensuous movements, and  then there is the lavishly named drummer Florian Pilkington-Miksa, a slim, serious, bespectacled figure, who is one of my personal all-time prog pin-ups. He now acts as director of the band, ensuring no cues are missed at the start and the varying tempos are maintained throughout.

With them now are the solid, no-nonsense bass player Chris Harris, the elfin-featured, intense keyboards player Robert Norton, flamboyant guitarist Kirby Gregory who joined them on their 1973 album Air Cut and later wrote Stretch’s smash hit Why Did You Do It, and the ever-animated Paul Sax on violin.

It’s a formidable line-up for a band, whose other illustrious alumni have included Darryl Way (Wolf), Francis Monkman (later with Sky), Eddie Jobson (Roxy Music, UK,  Yes, Jethro Tull and Frank Zappa) and Stewart Copeland (The Police).

Having toured extensively together, the band’s a tight and well-regimented unit but, on this night, they are electrifying.

Kristina, always a dazzling, bewitching presence, clad in sparkling black, commands the entire stage, her voice sultry and seductive, happy to shake hands and engage directly with members of her adoring audience during the songs.

She looks relaxed and happy, the mistress of all she surveys around her. Touchingly at one point, Gregory puts his arm around her and thanks her for inviting him to join the band. There are smiles all around. It’s that kind of evening.

And the music itself? The band kicks off with the instrumental Spider which gives them a chance to warm up their musical chops before Kristina saunters on stage and launches into the traditional opener, Young Mother, still a startlingly powerful song with lots of mesmeric, swirling synths and searing violin courtesy of Messrs Norton and Sax.

The early part of the show is devoted to the new material from their excellent album North Star released last year, most poignantly Stay Human, which Kristina wrote about the current world conflicts about which she reminded everyone before launching into the song.

The new material namely Time Games, Images & Signs and Interplay are more sophisticated than their earlier material but this gives both Gregory and Sax the chance to stamp their distinctive marks. Interplay in particular is a jazzy little gem. In the middle of these modern renditions comes Kristina’s folkie classic Melinda More Or Less, on which she plays her trusty multi-coloured acoustic guitar to tell the story of her troubled friend, who lived in a dream world.

All the band’s heroines seem to have had a torrid time: witness Marie Antoinette and Emily-Jane, The Purple Speed Queen, but they are both part of the greater story.

Also from Air Cut came Easy, followed by the majestic Metamorphosis, a true prog epic which has now been given a whole new lease of life through Norton’s beautiful, delicate piano solo that the whole band stop to acknowledge – and admire.

Finally, cometh the hour, cometh the band and cometh the memories as a backdrop appears of Air Conditioning’s hypnotic album cover.

The band look slightly apprehensive about enormity of the task ahead, playing all of the album tracks but not necessarily in the right order. They start gently with the luscious instrumental Rob 1, Sax offering a beautiful expressive touch to the haunting violin part.

That paves the way for the glorious It Happened Today, still truly one of the outstanding opening tracks on any prog album.  Kristina attacks it full-on with Gregory, Pilkington-Miksa, Norton and Harris all rocking out before it melts into the gorgeous closing violin solo, again Sax totally owning the piece while Kristina wafts around the stage, beckoning us all to join them in this magical musical web now being woven.

The gentle melody of Screw belies the song’s seriously menacing lyrics, followed by the brilliant uptempo Hide And Seek, a nightmare vision of an apocalypse survivor, that still sounds powerful, and the equally doomy Situations.

For the first time live, the band tackle Blind Man, a quaint little ditty about one man and his dog, the staccato vocal phrasing from Kristina based on Donovan’s Hurdy Gurdy Man, so it is not an easy song to sing.

And what’s this? Dancing? It is hard to resist the wonderful rhythmic Stretch that motors along at a rapid pace while Propositions packs a punch, Kristina screaming, the guitar, keyboard and violin creating a wonderful jagged cacophony.

So to Vivaldi and yes, that really is the original violinist Darryl Way walking on stage, moustachioed and grinning. With Way now clutching a traditional wooden violin rather than the cutting edge perspex model of the early 70s, we were all suddenly transported back to our youth, with those frenzied opening bars then exploding into life as the rest of the band join in. Way’s touch is still remarkable, his solo as moving and intense as the original. Your humble reviewer finds herself retreating and weeping with the sheer emotion of the moment.

Then they are joined by Ian Eyre, sporting a jaunty cap, who was Curved Air’s bass player on Air Conditioning.

The band does not even leave the stage but plunge straight into the encore as prolonged cheering keeps them in situ up there where they belong.

Air Conditioning duly delivered and sounding in terrific fettle, it’s left to Kristina to introduce their greatest hit, Backstreet Luv, followed by the frantic Everdance. Sax and Way are having a ball.  They work well side by side, the superb violinists that they are, each with their contrasting styles, Way the classicist and Sax the jazzy individualist, who have both brought so much to the band’s unique style.

This was a celebration rather than a concert, the night of shared happy memories epitomised by the bond that connects the band and fans.  For my part, it was also a celebration of where my prog journey originally started – on holiday in Majorca where an “older man” introduced me to Curved Air – and Jimi Hendrix.

So if anyone reading this knows a guy called Andy McCracken, who originally comes from Watford, now believed to be a practising Rastafarian living in Hertfordshire, possibly Hemel Hempstead, just tell him that Alison said thank you.