Thomas Lydwell Eckersley FRS[1] (27 December 1886 – 15 February 1959) was an English theoretical physicist and engineer.

[1][3] Eckersley was born in St John's Wood, London,[4] the second of three sons of William Alfred, a civil engineer, and Rachel, fifth child of Thomas Henry Huxley.

He joined the National Physical Laboratory (NPL), where he worked on the behaviour of iron under the influence of alternating magnetic fields.

A key piece of work in which he was involved was the analysis of the findings of the research team sent to Australia by the Marconi company to study long-wave propagation.

[6] In 1940 Eckersley joined the staff of the Air Ministry for secret work and in 1942 became Chief Scientific Adviser to the Interservice Ionosphere Bureau,[7] established at the Marconi Research and Development Laboratories at Great Baddow.