British Jazz Rock Rediscovered by Esoteric Recordings
Every now and again a box set arrives that does more than simply gather together a few albums in one place. It opens a door. It invites you into a world you may have missed, or perhaps only half-knew, and suddenly a whole area of music starts to glow with new life.
That is what Esoteric Recordings have done with Upward Curve: The Recordings 1973–1976 by Isotope.
This new 3CD clamshell box set brings together the complete studio output of one of Britain’s most exciting jazz rock fusion bands of the 1970s: Isotope from 1974, Illusion from later the same year, and Deep End from 1976. As with so many Esoteric releases, this is not just a reissue for the sake of it. It feels curated, cared for and presented with a real sense of purpose.
The three discs come in individual card sleeves, each reflecting the original album artwork, and the accompanying booklet includes a detailed essay by Sid Smith, along with photographs, track information and personnel details. The set has been remastered from the original master tapes by Ben Wiseman, and the involvement of the Esoteric team gives it that familiar quality stamp collectors have come to expect.
For fans of British jazz rock, Canterbury-related music, progressive rock and instrumental fusion, this is a very welcome release.
British Jazz Fusion – The Hidden Story
When people talk about jazz fusion, the conversation often moves very quickly across the Atlantic. We think of Miles Davis opening the door with his electric period, and then the great waves that followed: Mahavishnu Orchestra, Return to Forever, Weather Report, Herbie Hancock, Billy Cobham, Stanley Clarke, Lenny White, Al Di Meola and so many others.
Those albums became the reference points. For many of us, records like Romantic Warrior by Return to Forever or Spectrum by Billy Cobham became the benchmark for what jazz rock could be: technical, exciting, electric, melodic and fearless.
But Britain had its own story.
We had Soft Machine. We had Nucleus. We had Back Door. We had Allan Holdsworth moving through different worlds. And we had Isotope, a band who, for whatever reason, never quite became as widely known as they deserved to be.
Listening to Upward Curve now, what strikes me most is how alive this music still sounds. This is not something that feels trapped in a specialist corner of the 1970s. It is vibrant, melodic, muscular and full of movement. It still has that feeling of musicians pushing each other, listening to each other, and discovering where the music can go in real time.
Who Were Isotope?
Isotope were formed in the early 1970s by guitarist Gary Boyle, a remarkable player who had already worked with Stomu Yamashta’s East Wind. The original line-up featured Gary Boyle on guitar, Brian Miller on keyboards, Jeff Clyne on bass and Nigel Morris on drums and percussion.
Clyne had previously played with Ian Carr’s Nucleus, which gives you an immediate sense of the musical territory we are in. This was British jazz rock at a high level, played by musicians who understood both the discipline of jazz and the power of rock.
Across these three albums the line-up changed, and that becomes part of the story of the box set. The first album is largely driven compositionally by Brian Miller, while Gary Boyle is more of a featured instrumental force. By the second album, Illusion, Boyle becomes more central as a writer, and the arrival of Hugh Hopper from Soft Machine on bass and Laurence Scott on keyboards gives the music a different edge. By Deep End, the band has moved again, with Dan K. Brown on bass, Zoe Kronberger and Frank Roberts on keyboards, and Morris Pert adding percussion.
That changing personnel gives each disc its own character. This is not simply three albums that sound the same. You can hear the music evolving.
Disc One: Isotope – The Beginning
The debut album, Isotope, was released in 1974 on Gull Records, a label many rock fans will also associate with the first two Judas Priest albums. The album features Gary Boyle on guitar, Brian Miller on keyboards, Jeff Clyne on bass and Nigel Morris on drums.
What I love about this first album is that it already has a strong identity. It is jazz rock, yes, but it is not cold or academic. There are melodies here. There is groove. There is a sense of optimism and exploration.
Brian Miller is the dominant composer on much of the album, and that gives the record a particular shape. Tracks such as “Then There Were Four”, “Do The Business” and “Upward Curve” have that fusion energy, but there is also a very British quality in the way the themes unfold. Gary Boyle’s own composition “Honkey Donkey” gives an early indication of where his writing might go later, but even when he is not the main composer, his guitar is absolutely central to the sound.
And what a player he is.
Gary Boyle’s guitar work is fluid, fiery and expressive without ever tipping into empty display. He has the speed and technique, but he also has touch. There is a voice in his playing. You can hear the jazz phrasing, the rock attack and the melodic instinct all working together.
The bonus material on the first disc is also important. The BBC Radio 1 In Concert tracks from October 1973 show Isotope as a fiery live band. These performances have a real spark to them. You can hear them stretching out, and the music feels less polished but more dangerous. For collectors, this is exactly the kind of bonus material that adds value to a set like this. It is not filler. It tells you more about who the band were.
Disc Two: Illusion – The Classic Statement
For many, Illusion is the key Isotope album, and listening to it as part of this set, it is easy to hear why.
Released in November 1974, Illusion came after major personnel changes. Brian Miller and Jeff Clyne had left, and the new line-up brought in Hugh Hopper on bass and Laurence Scott on keyboards. Nigel Morris remained on drums, and Gary Boyle moved further forward as a writer and bandleader.
This is where the music becomes more aggressive, more rock-orientated and, in places, more experimental. Hugh Hopper’s bass sound, particularly that unmistakable fuzz bass tone associated with his Soft Machine work, adds a very different texture. The music has more bite. It feels tougher. There is a stronger sense of interplay between guitar, bass and keyboards.
The title track sets the tone, but it is pieces like “Spanish Sun”, “Sliding Dogs / Lion Sandwich”, “Golden Section” and “Temper Tantrum” that show the breadth of what this line-up could do. There is a restless quality to the album. It never sits still for long, but it remains tuneful and accessible enough to draw in listeners who may not consider themselves full-on jazz fusion fans.
What is fascinating is how this music mirrors what was happening globally in fusion at the time. In America, jazz rock was becoming more electric, more rhythmically driven, more open to funk and rock textures. Isotope were not following a dead end or operating in isolation. They were moving with the same current, but with a distinctly British sensibility.
The bonus tracks on disc two come from a 1974 BBC TV Old Grey Whistle Test session, featuring “Bite On This” and “Upward Curve”. Again, this is invaluable material, because it captures another dimension of the band. It also makes you wish more visual footage survived, because Isotope were clearly a group who came alive in performance.
Disc Three: Deep End – Funk, Rhodes and a Changing Landscape
By the time we reach Deep End in 1976, the musical landscape has changed again. Isotope’s line-up now includes Gary Boyle and Nigel Morris, with Dan K. Brown on bass, Zoe Kronberger and Frank Roberts on keyboards, and Morris Pert on percussion across much of the album.
The sound shifts accordingly. There is more Fender Rhodes, more funk, more groove, and a slightly smoother production feel. This is still Isotope, but it is not the same Isotope as the first album. The fusion vocabulary is expanding, and you can hear the influence of what was happening in jazz rock more broadly during the mid-1970s.
Tracks such as “Mr. M’s Picture”, “Crunch Cake”, “Black Sand” and the title track “Deep End” show a band still full of ideas. The music has a strong rhythmic base, and the keyboards give it a warmer, more colourful texture. Some listeners may prefer the sharper edges of Illusion, but I found Deep End very enjoyable. It has a flow that makes it easy to return to, and it shows a band that was still developing rather than standing still.
The 2001 remixes included as bonus tracks are interesting additions. They do not replace the original album, but they give another perspective on several key pieces, including “Mr. M’s Picture”, “Crunch Cake”, “Black Sand” and “Deep End”.
The Musicians
Across the three discs, the musicians featured include:
Gary Boyle – guitars
Brian Miller – keyboards
Jeff Clyne – bass
Nigel Morris – drums and percussion
Laurence Scott – keyboards and additional synthesizer
Hugh Hopper – bass
Zoe Kronberger – piano, Fender Rhodes, synthesiser, clavinet and vocals
Frank Roberts – piano, Fender Rhodes and synthesiser
Dan K. Brown – bass
Morris Pert – percussion
Neville Whitehead – acoustic bass
That list alone tells you a great deal about the quality of musicianship involved. These were not casual players dipping into jazz rock because it was fashionable. These were serious musicians with real pedigree, imagination and technique.
Gary Boyle, in particular, deserves far greater recognition. Hearing him across these three albums, you realise what a superb guitarist he was: lyrical, fast, inventive, but always musical. His tone and phrasing are a major part of why this set works so well today.
It is also good timing that Esoteric are continuing the story with Gary Boyle’s solo work. His post-Isotope albums deserve to be heard by a wider audience too, and this Isotope box set may well send many listeners in that direction.
Presentation and Sound
As a physical release, Upward Curve does exactly what it needs to do. It is compact, attractive and informative. The individual sleeves are simple but effective, and the booklet is excellent. Sid Smith’s essay gives the music context without overwhelming it, and the photographs help place the band in their time.
The remastering is also very sympathetic. The sound has clarity and presence, but it does not feel artificially modernised. This is especially important with music like this, where dynamics and instrumental separation matter. You want to hear the bass moving, the drums shifting, the keyboards adding colour, and the guitar cutting through without everything becoming compressed into one block of sound.
The BBC material has the expected difference in source and feel, but that is part of its charm. It adds energy and historical weight to the set.
One of the reasons I value releases like this is that they help correct the story.
British jazz rock has too often sat in the margins. People know the big American names. Progressive rock fans know some of the crossover points. Canterbury fans know where to look. But bands like Isotope can still feel like hidden chapters.
Esoteric are doing important work by making this music available again in well-presented, affordable physical editions. This is exactly the kind of release that allows listeners to reassess a band properly. Not from a single second-hand copy, not from a poor transfer online, but from the original albums, remastered and gathered with the right supporting material.
For me, Upward Curve is not just a box set for existing Isotope fans. It is an invitation. If you enjoy Return to Forever, Mahavishnu Orchestra, Billy Cobham, Soft Machine, Nucleus, Back Door or Allan Holdsworth, there is something here for you. If you are a progressive rock fan who wants to move a little further into jazz fusion, this is a very good place to start.
It is another excellent release from Esoteric Recordings and a reminder that British jazz fusion had its own voice, its own fire and its own forgotten treasures.
Isotope deserve to be heard again.
