He was born in Bickley, Kent, England,[1][2] the second of five sons.
His younger brother, Sir Jasper Hollom, was Deputy Governor of the Bank of England from 1970 to 1980, having been Chief Cashier of the Bank of England from 1962 to 1966.
[3] In March 1951 he became a member of the editorial board of British Birds magazine[1] under the senior editorship of Max Nicholson, whom he succeeded in 1960.
[4] Hollom was a Council member and Vice President of the Ornithological Society of the Middle East.
[5] He was the first chairman of the British Birds Rarities Committee[1] and was awarded the British Trust for Ornithology's Tucker Medal in 1954[6] and the British Ornithologists' Union's Union Medal "for his outstanding contribution to the BOU and to ornithology" in 1984.