Born Wilfrid von Glehn in Sydenham, London, his father was an Estonian coffee importer and his mother was French. He studied briefly at South Kensington School of Art (c1889), and then for six years at the Ecole des Beaux Art in Paris under Elie DELAUNAY and Gustave MOREAU.

He began to exhibit at the 1895 Paris Salon and at the Galerie Durand-Ruel (New York). In the 1890s he was to make a close friend of the artist John Singer Sargent, whose influence had a lasting effect upon his work, and went to America to assist him with a mural commission for the Boston Public Library.

In 1904 he married Jane EMMETT (aka Jean), an American from a distinguished New York family of artists whom he had met the previous year. They honeymooned in Cornwall, his first visit having been in 1901. From 1905 until 1914 the couple travelled throughout Europe and America before joining the British Red Cross staff in France in 1915.

On their return to England the following year he was commissioned in the Artists Rifles, and seconded to the Front in Italy in 1917. That year the family changed its name from von G to De Glehn.  Returning to England in 1919, he held a solo exhibition at the Leicester Galleries. In 1921, after spending some time in Cornwall the previous year, a one man show in New York was mounted.

In 1923 he spent the summer in Cornwall before travelling again to France; thereafter he established a 'remote Cornish studio' to which he came with regularly 'with his charming American wife'. Jean also painted but did not display her work publicly ('Round the Studios', The Artist, 1932).

In 1942 the family moved to Wiltshire. He painted, travelled and exhibited widely, and during visits to Cornwall painted around Falmouth, Polperro and Cadgwith.