At 58 metres in height, it is the world's second tallest fire-lookout tree (second only to the nearby Dave Evans Bicentennial Tree), and visitors can climb up to a platform in its upper branches for views of the surrounding karri forest. It is owned by the Shire of Manjimup.
Built in 1947, the Gloucester Tree was one of eight karri trees that between 1937 and 1952 were made relatively easy to climb so that they could be used as fire lookout spots. The suitability of the tree as a fire lookout was tested by forester Jack Watson, who climbed the tree using climbing boots and a belt. It took Watson six hours to climb 58 metres, a difficult climb due to the 7.3 metre girth of the tree and the need to negotiate through limbs from 39.6 metres up. Jack Watson, a Gallipoli veteran, was also Superintendent of Kings Park in Perth, and retired from that position in 1962.
Another forester, George Reynolds, pegged the ladder and lopped branches to facilitate climbing the tree, and a wooden lookout cabin was built 58 metres above the ground. The Governor-General of Australia, Prince Henry, Duke of Gloucester, visited the site during construction, and the tree and national park are named in his honour.
The wooden lookout cabin was demolished in 1973 for safety reasons, and was replaced with a steel and aluminium cabin and visitors' gallery. Currently the climb is done by stepping on 153 spikes that spiral the tree.
- Australian Broadcasting Corporation. Radio National (17 December 2007), The world's tallest tree, Australian Broadcasting Corporation, retrieved 12 March 2015
- "NatureBase - Gloucester National Park". Retrieved 18 January 2008.
- Wright, G.W (1946), G.W. Wright personal film [The Duke and Duchess of Gloucester at Pemberton], G.W. Wright, retrieved 12 March 2015
- Bain, Andrew (21 February 2006). "Jolly green giants". The Australian. Retrieved 4 April 2012.
- "CLIMBING THE GLOUCESTER TREE". The Australian Women's Weekly. National Library of Australia. 27 November 1968. p. 161 Supplement: Holidays in Australia. Retrieved 12 March 2015.