He was the nephew of Zulu War Victoria Cross recipient Nevill Coghill and the cousin of the Irish novelist Edith Anna Somerville.

[3] Coghill was educated at Haileybury College in Hertfordshire following which he was commissioned as a second lieutenant in the South Wales Borderers (in which his late uncle had famously served in the Zulu War in 1879) and served with the East African Civil Service.

[4] Coghill served in the Royal Naval Volunteer Reserve during World War II gaining the rank of lieutenant-commander.

His acting roles included: Avarice in the film Doctor Faustus (1967), written and co-directed by his brother Nevill Coghill (1899–1980); Lt. Col. Douglas in the film The Charge of the Light Brigade (1968); Colonel in Whistle and I'll Come to You (1968); His Father (uncredited) in Oh!

What a Lovely War (1969); Cochefer in The Elusive Pimpernel (1969); Alderman in Canterbury Tales (1969); Colonel in "The Hunting of Lionel Crane" episode of The Wednesday Play (1970); Museum Curator in The Stalls of Barchester (1971), and Daniels in Six Days of Justice (1972).