Hugh Murton Le Fleming was born on 11 June 1902, the son of Dr Ernest Kaye Le Fleming and Florence M. Beeching. Le Fleming graduated from Clare College, Cambridge, in Mechanical Engineering, and completed an apprenticeship with the Great Western Railway at their Swindon Works. He then worked as an inspector for the Crown Agents for the Colonies, checking and testing steam locomotives before they were shipped out to their customers across the world. In 1929 he was appointed District Locomotive Superintendent at Ipoh with the Federated Malay States Railways. Two years later Le Fleming was transferred to the Central Workshops of the FMSR in Kuala Lumpur.

In 1927 Le Fleming had married Rosalind Beatrice Benedicta Lees (born 9 July 1901), and she joined him in Malaya. Rosalind had spent her childhood in Tientsin, China, and studied modern languages at Royal Holloway College. She contributed to periodicals in Malaya and South Africa and published two novels in the 1930s. Their son, Laurence Stephen Kaye Le Fleming, was born in 1936. Early in 1941 Hugh took leave with Rosalind, her mother Mrs. B.M. Lees and Stephen in South Africa, apparently without intending to return, but to leave the family in Cape Town and continue back to the United Kingdom alone. This he did in about April 1941. During the Second World War he worked in the Admiralty's engineering offices in Bath. Rosalind worked in the office of the Free French in Cape Town until 1944, when she and the family travelled to England. Neither Hugh nor Rosalind returned to Malaya.

Le Fleming had an active social life and travelled widely within Malaya and the region. He was an enthusiastic lepidopterist and was also interested in merchant shipping lines. His major interest remained the steam locomotive, of which he had encyclopaedic knowledge. Le Fleming was also a gifted amateur painter, and his interests in butterflies, landscapes, steam ships and locomotives were frequently reflected in his subjects. Some of his art work featured in promotional material for the FMSR.