[1] He was educated at Marlborough College, then studied zoology at Oxford University, where his doctoral thesis was on the sexual behaviour of newts.

[1] He played a key role in organising the 1989 'First World Congress of Herpetology' at the University of Kent, and was instrumental in the creation of the Declining Amphibian Populations Task Force, and served as its international director from 1994 to 2006.

[3] Between 1990 and 1998 he seat on the council of the Zoological Society of London (ZSL), as well as chairing its conservation committee.

[1] He died on 10 April 2019, after being diagnosed with an rare and incurable form of T-cell lymphoma in 2016.

[6] An ZSL symposium on amphibian diseases held in late April 2019 was also dedicated to Halliday.