Physicist and electrical engineer

Due to copyright issues we are not able to show you a photograph of Professor Barlow but you can see one on the NPG website.

Harold was the son of electrical engineer Leonard Barlow and his wife Catherine (nee Monteagle); he lived at Penrith, Hookfield Road, Epsom for much of his married life, until his death. The Barlow children were as follows.

Name Born Married Died
Leonard Monteagle 5.6.1898 Highbury - 5.2.1918 Martlesham, Suffolk
Harold Everard Monteagle 15.11.1899 Highbury/Islington Janet Hastings Eastwood 20.4.1989 Epsom
Kathleen Margaret Monteagle*
16.5.1901 Holloway Howard Charles Planterose 1971 Surrey SW
Lilian Atlee Monteagle 29.3.1904 Leytonstone Edward Eric Stimson 1995 Rugby
Donald Spiers Monteagle FRCS 4.7.1905 Leytonstone Elizabeth Maciver 5.7.1994 Herts
Stuart Lansdale Monteagle CBE**
(director/chairman of electrical engineering companies)
28.9.1908 Wallington Margaret Winifred Goudge 1974 London City
*lived in Tabor Gardens, Epsom at one point
**lived in Ewell Downs Road at one point

Leonard Monteagle Barlow
Lieutenant Leonard Monteagle Barlow (1898-1918)

Leonard was a flying ace in the First World War, credited with 20 kills; he held the Military Cross with two Bars for his bravery. Ironically he was not killed in combat, but perished when a Sopwith Dolphin that he was test-flying broke up in mid-air. He is buried in Bandon Hill Cemetery, Wallington.


Harold followed in his father's footsteps and in 1917 he graduated from Finsbury Technical College as an electrical engineer. He then joined the RNVR, doing experimental work at the Portsmouth signal school. After the War he attended University College London (UCL) and graduated in 1920 with first class honours, following which he worked in research with Sir Ambrose Fleming.

Leonard Barlow had his own consultancy business and Harold initially joined the family firm, but he was more at home in academia and in 1925 he returned to UCL as an assistant lecturer, carrying out work on Ohm's law at high current densities (as you may recall from school physics lessons Ohm's law is a formula which measures current resistance in amps); he also invented a valve ammeter (used to measure electrical current) and a system for protecting fluorescent tubes.

Harold became a reader at UCL and when the Second World War broke out he was chosen to work on radar development, which was to prove so vital to the Allies during the hostilities; he then became superintendent of the Royal Aircraft Establishment's radio department. The significance of this work to Harold personally was that he saw how the microwaves used in radar could have civil uses. (The now ubiquitous microwave oven, patented in America in 1945, emerged from this type of research and, as an aside, the first commercially produced model was approximately 6 feet tall).

When hostilities ceased Harold again went back to UCL as a professor of electrical engineering, ending up as Head of Department, and conducted influential research which impacted on telecommunications. Over the years he received many honours, including Fellowship of the Royal Society in 1961. Even after his retirement from UCL in 1967 he remained there, engaged in research on optical fibres which today underpin the internet, the mobile phone network, cable TV and many other applications. Sadly, arthritis ultimately prevented him from travelling up to London, but he continued his work at home. He died on 20 April 1989, having suffered from cancer.


In 1931 Harold married Janet Hastings Eastwood (1904-1990), daughter of a Presbyterian Minister. It was undoubtedly Janet's childhood in Penrith, Cumberland that resulted in their marital home being named 'Penrith'. There were four children, being Colin Hastings (1932), David M (1937), Neil W (1941) and Lindsay M (c.1944).


You will notice that I have not dwelt overmuch on the work that Harold Barlow did and that is because it is too technical for an article of this kind. However, there is plenty of material on the internet which explains in detail the principles of his subject-matter and the importance of the kind of research he was engaged in.

Researched and written by Linda Jackson ©2014