Born in London in 1915, he was the second son of Sir Alan Barlow, son of Sir Thomas Barlow, royal physician. His mother was Lady Nora Barlow, daughter of Sir Horace Darwin. He was a great-grandson of the naturalist Charles Darwin.
He married Brigit Ursula Hope Black (known as Biddy), daughter of the author Ladbroke Black in 1938.
He was educated at Marlborough College, and Trinity College, Cambridge, where he studied medicine. He also studied at University College London.
He was named after his great-great-great-grandfather Erasmus Darwin. They had three children: Jeremy Barlow (b 1939), flautist and Director of the Broadside Band, married Jane Marian Hollowood Camilla Barlow (b 1942), married Martin Christopher Mitcheson Officer of the Most Excellent Order of the British Empire, doctor, and later Anthony Whitworth-Jones, Director of Garsington Opera Phyllida Barlow (b 1944), sculptor and Professor of Fine Art at the Slade School of Fine Art in London, who married Fabian Peake, son of the artist Mervyn Peake. Barlow published research papers in physiology and psychiatric medicine.
In 2008 the society started the Erasmus Darwin Barlow Conservation Expeditions named in his honour.
Barlow was also a trustee for over 20 years of the Barlow Collection of Oriental art collected by his father. Barlow died in Cambridge from renal failure in 2005.
Barlow was senior lecturer and honorary consultant in psychological medicine at Street Thomas’s Hospital Medical School (1951-1966), vice chairman of the Mental Health Research Fund, and a member of the scientific staff of the Medical Research Council Department of Clinical Research, University College Hospital. He was chairman of the Bath Institute of Medical Engineering and an enthusiastic founding member of the Erasmus Darwin Foundation at Lichfield.
