Born in Kidderminster, Worcestershire, Forgeham moved to Erdington, Birmingham as a child, and trained at the Royal Academy of Dramatic Art (RADA) on a two-year scholarship (1962–64) and graduated with a RADA Silver medal for Best Performance student. He was a member of the Royal Shakespeare Company (RSC) (from 1966 until 1972) and toured with the company both nationally and internationally. Whilst on tour in Australia he decided to stay longer than anticipated and founded the Globe Shakespeare Theatre in Sydney.
Film appearances include: The Italian Job (1969), Adolf Hitler: My Part in His Downfall (1973), Spy Story (1976), Sheena (1984), Pope John Paul II (1984), The Laughter of God (1990), King of the Wind (1990), The Young Americans (1993), Staggered (1994), The Road to Ithaca (1999), Kiss of the Dragon (2001), Mean Machine (2001), Pledge of Allegiance (2007), Torture Room (2007) and Dead Man Running (2009).
In 2004 he appeared in the second series of the ITV weight loss show, Celebrity Fit Club. He replaced Freddie Starr as team captain, but was demoted five weeks later, the role being taken by James Whitaker.
Forgeham died suddenly from internal bleeding after breaking a collarbone after falling out of bed at his home in Worthing, West Sussex on 10 March 2017, aged 75.
