Formed in September 1971 by multi-talented guitarist Rob MacKenzie, and featuring the flying elbows of electric viola player Cleis Pearce, -MacKenzie Theory forged an identity as one of Australia's truly mind-blowing progressive rock bands. The band consistently enthralled festival and concert audiences with a dynamic instrumental sound that embraced elements of Santana (circa Caravanserai), King Crimson, John Coltrane and Mahavishnu Orchestra.
While Rob MacKenzie was getting MacKenzie Theory off the ground, he played as a guest guitarist with a number of bands, including Friends and Billy Thorpe and the Aztecs. As the band's popularity grew, MacKenzie Theory made regular appearances alongside the likes of Spectrum, Madder Lake, Chain, The Aztecs and Band of Light. The first MacKenzie Theory recording, the eight-minute `New Song and', appeared on the live Various Artists triple album The Great Australian Rock Festival Sunbury 1973, issued on Mushroom (April 1973). Although the live-in-the-studio album Out of the Blue (July 1973) did not do justice to the band's powerful stage presence, it did combine classical elements, majestic jazz-fusion and hard rock in a suitably cosmic fashion. In September 1973, both Leadabrand and Majewski left the band to be replaced by Paul `Sheepdog' Wheeler (bass; ex-Billy Thorpe and the Aztecs, Band of Talabene) and Greg Sheehan (drums; ex-Blackfeather). Peter Jones also joined on electric piano.
In 1974, MacKenzie became one of the first musicians in Australia (along with folkie Glenn Cardier and Greg Quill from Country Radio) to receive a travel grant from the Australia Council for the Arts (under the auspices of Gough Whitlam's Labor government). MacKenzie and Pearce travelled to the UK, which effectively ended MacKenzie Theory's career. To mark the band's demise, Mushroom Records recorded the farewell concert (Melbourne's Dallas Brooks Hall, 15 May 1974) and issued the results as Bon Voyage. Once again, the album only offered a superficial glimpse into the band's live power. Nevertheless, epic tracks like `Clouds' and `Supreme Love' were at times sweet and dreamy, at others frantic and chaotic.
Mushroom included a different version of `Supreme Love' on the budget album Highlights of Sunbury '74 Part 2. In 1994, reissue specialists Raven included `Extraterrestrial Boogie' (from Out of the Blue) on the Various Artists collection Golden Miles: Australian Progressive Rock, 1969�1974. In the 1980s, MacKenzie moved to the USA, where he has since earned a respectable living as guitarist with rock'n'roll revival act Sha Na Na.