[1][2] Brain was educated at Mill Hill School and New College, Oxford, where he started to study history, but disliked it.

The First World War having begun in 1914, the following year he joined the Friends' Ambulance Unit as an alternative to volunteering for combat, and was sent to York, moving later to the King George Hospital in London, attached to the X-ray department.

Apart from his clinical practice, he was a member of a large number of government committees pertaining to physical and mental health, and was involved in the care of Winston Churchill on the latter's deathbed in 1965.

[citation needed] He was knighted in 1952,[3] made a baronet on 29 June 1954,[4] and on 26 January 1962, was created Baron Brain, of Eynsham in the County of Oxford.

[7] In this address he discussed how humanity was approaching the anthropocene and he reiterated Alfred North Whitehead's warning that "A muddled state of mind is prevalent.