Orange was born in 1935, in Shildon, County Durham and was educated at St. Mary's Grammar School, in Darlington, and at Hull University. Orange served in the Royal Air Force from 1953 to 1956.

In 1962 he went to live in New Zealand and taught History at the University of Canterbury in Christchurch until he retired in 2002.

He is married to Sandra, and has a stepdaughter Sarah.

In his younger days, Dr Orange had parts in 20 stage plays and 50 radio plays. He also appeared regularly on television, commenting on current affairs.

Among Orange's many peer reviewed articles is: "Cutting through the Political Jungle: Eisenhower and Tedder as Allies and Friends, 1942-1945." Air Power Review Vol. 3 No. 4 (Winter 2000), pp. 75—86.

Orange has published eight books, and numerous articles and conference papers including:

• Dowding of Fighter Command: Victor of the Battle of Britain, (Grub Street Pub, Sep 2008)
• Johnny Checketts: The Road to Biggin Hill, (Grub Street; New title edition, Mar 2007)
• Slessor: Bomber Champion - The Life of Sir John Slessor, (Grub Street Pub, Oct 2006)
• Tedder: Quietly in Command, (Routledge Pub, Apr 2004)
• Winged Promises: History of No.14 Squadron, RAF 1915-1945, (Weidenfeld & Nicolson, Nov 1998)
• Ensor's Endeavour: A Biography of Wing Commander Mick Ensor, (Grub Street, May 1994)
• Straight and Level, (Grub Street, Oct 1993) with Kenneth Cross
• Coningham: A Biography of Sir Arthur Coningham, (Methuen Publishing Ltd, Feb 1990)
• The Road to Biggin Hill, (Airlife Publishing Ltd, Feb 1987)
• Park: The Biography of Air Chief Marshal Sir Keith Park, (Methuen Publishing, Aug 1984)