His father, John Patrick Cronin (1889–1952), a director of Lever Brothers, was Lord Leverhulme's representative in India and later Chairman of Horlicks, Australia.

Cronin spent the first three years of his life in India until the family returned to their home in Hornsey Lane, Highgate, London in 1919.

Cronin wanted to join the Royal Navy, but his father decided he was to have a career in medicine, and sent him to St Bartholomew's Hospital Medical College.

He became vice chairman of the North St Pancras Labour Party in 1950, and was a member of London County Council, representing Fulham East, from 1952 to 1955.

On 18 November, while taking part in a scheme for Parliamentarians to visit Royal Navy ship at sea, he was one of three survivors from a Wessex helicopter belonging to HMS Hermes which crashed off St David's Head.

A keen sportsman who hunted when young and regularly rode Household Cavalry horses in Hyde Park, he also played polo, squash and tennis.

In the late afternoon his horse returned home without him: it was feared he might have been thrown and that he could be lying badly injured in freezing weather conditions.

His funeral was held at Minstead Church and Sir Ernie Harrison, Chairman of Racal and a close friend, made a valedictory speech from the pulpit during the service.