Egerton was born in Glyn Cywarch, near Talsarnau, Gwynedd, Wales, on 11 October 1886, the fourth son of Colonel Sir Alfred Mordaunt Egerton, an officer of the Rifle Brigade and the Royal Horse Guards, and Comptroller to the Duke of Connaught and Strathearn, and his wife, The Honourable Mary Georgina Ormsby-Gore, the oldest daughter of William Ormsby-Gore, 2nd Baron Harlech.

[1][2] After graduating from Eton in 1904, he entered University College, London, where he read chemistry under the tutelage of Sir William Ramsay.

He intended to then proceed to Germany, but this was cut short in 1909 by an offer of a position as an instructor at the Royal Military Academy, Woolwich.

[2] Later that year he joined the Clarendon Laboratory at Oxford University, where he succeeded Henry Tizard as Reader in Thermodynamics in 1923.

During the Second World War he pioneered the use of liquid methane as an alternative to petrol as a fuel for motor vehicles.

In this, he was successful, establishing good relations with American scientific administrators such as Vannevar Bush and James Conant.

[2] He was knighted for his services on 1 January 1943,[4] an honour which King George VI conferred on him in a ceremony at Buckingham Palace on 9 February 1943.

He was the Chairman of the Scientific Advisory Council of the Ministry of Fuel and Power from 1948 to 1953, and was director of the Salters' Institute of Industrial Chemistry from 1949 to 1959.

Egerton died on 7 September 1959 at Mas del Soleou, a country estate in Mouans-Sartoux, France, that he had inherited from his mother.