The eldest daughter and co-heiress of the Hon. John Acland-Hood, a barrister and his wife, Phyllis (née Hallett), Elizabeth Acland-Hood was educated at Cheltenham Ladies' College and Girton College, Cambridge. Her father was himself a younger son of Alexander Fuller-Acland-Hood, 1st Baron St Audries.
Having graduated from the University of Cambridge, Acland-Hood worked as a schoolteacher, teaching mathematics. In 1967 she inherited from an uncle her family's ancestral seat, Fairfield House, near Stogursey, Somerset, and gave up her teaching career to concentrate on managing the estate which came with it.
In 1975, she married Sir Michael Gass KCMG, who died in 1983. He was a former High Commissioner for the Western Pacific (1969–71) and Governor of the Solomon Islands (1969–73), and they had no children.
From 1989 to 1993 she was Chairman of the Exmoor National Park Committee and at the same time was Vice-Chairman of the county council's Social Services Committee. In 1994 she was High Sheriff of Somerset, the next year was appointed a Deputy Lieutenant for Somerset, and in 1996 was promoted to Vice Lord-Lieutenant and appointed as a Justice of the Peace for the county. In 1998, she became Lord Lieutenant of Somerset, a position she held until March 2015. In 2011, she attracted considerable negative attention after selling some 230 acres of land on the coast beneath the Quantock Hills for about £50 million. The land was the part of her Fairfield estate lying immediately to the west of the Hinkley Point power station and was wanted for the construction of two new nuclear reactors.
- Director, Avalon NHS Trust, 1993–96
- Commissioner, English Heritage, 1995���2001
- Member of Committee of National Trust (Wessex) 1994–2002
- National Executive Committee, Country Landowners Association, 1998–2003
- Wessex Committee, HHA, 1998–present
- Wells Cathedral Council, since 2004
- Member of Council of Cheltenham Ladies' College, 1992–2001
- Member of Council of Bath University, 1999–2002
- Trustee of West of England School for Children with Little or no Sight, 1996–2008
- President, Royal Bath and West of England Society, 2002–03
- President, Somerset County Scout Council
- Patron, Somerset Sight
- Patron, British Red Cross in Somerset, 2013–present
- Vice-President Wessex Reserve Forces' and Cadets' Association 1998–2015
- Trustee, Calvert Trust Exmoor
- "The Lord-Lieutenant of Somerset". Somerset County Council. Archived from the original on 20 October 2013. Retrieved 6 August 2019.
- "Anne Maw appointed as Lord-Lieutenant for Somerset". Somerset County Gazette. 26 February 2015. Retrieved 4 March 2015.
- Profile, debretts.com; accessed '5 June 2014.
- "Nuclear land deal leaves Lady Gass '£50m richer'" Archived 4 December 2013 at the Wayback Machine, Bridgwater Times, 17 November 2011. Retrieved 2 May 2012.
- Profile, thepeerage.com. Retrieved 15 June 2014.
- "Election of Councillors for Count of Somerset" (PDF). Somerset County Council. 4 May 1989. Archived from the original (PDF) on 20 October 2013. Retrieved 18 October 2013.
- London Gazette, issue no. 55408 dated 19 February 1999.
- "Lady Gass appointed as new Somerset patron of British Red Cross". This is Somerset. Archived from the original on 5 January 2013. Retrieved 15 June 2014.
- "No. 60728". The London Gazette (Supplement). 31 December 2013. p. 4.
- Lady Gass, High Sheriff of Somerset, portrait by Hans Schwarz, 1996