Its roots lay in Vernon's mail order label Purdah Records, which released just four 7" singles; including "Flapjacks" by Stone's Masonry (featuring Martin Stone, later to join Savoy Brown and Mighty Baby); and another by John Mayall and Eric Clapton "Bernard Jenkins", and "Lonely Years". Only 99 copies of each are thought to have been pressed - limited originally to avoid purchase tax - although it has also been said that the number was as high as 500.
After briefly forming the Outasite label, Vernon switched to Blue Horizon in 1966, issuing singles and a small number of now-unobtainable albums by U.S. blues artists, including Doctor Ross. A world-wide licensing and distribution deal with CBS heralded the glory years of the label. Starting with two 7" singles with combined CBS/Blue Horizon stamps featuring Fleetwood Mac and Aynsley Dunbar there followed a string of singles and albums by both British and U.S. blues artists, both licensed and newly recorded. Some releases featured Mike Vernon produced recordings of U.S. artists such as Otis Spann and Champion Jack Dupree, backed by British blues players such as Peter Green, Rory Gallagher, Paul Kossoff, Stan Webb, Pete Wingfield and Duster Bennett.
The label produced chart hit singles for Fleetwood Mac and Chicken Shack and a string of albums in imaginative sleeves. The distinctive blue label singles eventually gave way to red and then no-centre white labels as the blues boom died away. The label ceased production around 1971, and all its titles are collectible today. Later vinyl re-releases by both Sire Records in the US and Line Records kept interest alive, but CD reissues were limited until Vernon himself re-emerged in the 21st century to remaster the best material and do justice to the Blue Horizon legacy.[original research?]
- Bob Brunning, Blues: The British Connection, Helter Skelter Publishing, London 2002, ISBN 1-900924-41-2 - First edition 1986 - Second edition 1995 Blues in Britain
- Bob Brunning, The Fleetwood Mac Story: Rumours and Lies, Omnibus Press London, 1990 and 1998, ISBN 0-7119-6907-8
- Martin Celmins, Peter Green - Founder of Fleetwood Mac, Sanctuary London, 1995, foreword by B.B.King, ISBN 1-86074-233-5
- Dick Heckstall-Smith, The safest place in the world: A personal history of British Rhythm and blues, 1989 Quartet Books Limited, ISBN 0-7043-2696-5 - Second Edition : Blowing The Blues - Fifty Years Playing The British Blues, 2004, Clear Books, ISBN 1-904555-04-7
- Christopher Hjort, Strange brew: Eric Clapton and the British blues boom, 1965-1970, foreword by John Mayall, Jawbone 2007, ISBN 1-906002-00-2
- Paul Myers, Long John Baldry and the Birth of the British Blues, Vancouver 2007, GreyStone Books, ISBN 1-55365-200-2
- Harry Shapiro, Alexis Korner: The Biography, Bloomsbury Publishing PLC, London 1997, Discography by Mark Troster, ISBN 0-7475-3163-3
- Mike Vernon, The Blue Horizon story 1965-1970 vol.1, notes of the booklet of the Box Set (60 pages)