Lancelot de Giberne Sieveking (1896-1972) published as Captain L. de G. Sieveking and L. de Giberne Sieveking, but later in life just called himself Lance Sieveking. His first book was published in 1919, and he published several science fiction novels in the 1920s, and one in the 1950s. He was the son of a timber merchant, Edward Sieveking, and a suffragist and writer, Isabel Giberne (the cousin of Gerard Manly Hopkins). Lancelot was the god-son of G.K. Chesterton, who was a considerable influence on him. He went to prep school, but from the age of 13 was educated at home. He began his first novel, Stampede!, at the age of thirteen, although it was not published until 1924.
After his war service, he went to St Catherine’s College, Cambridge, but he failed to qualify for the English tripos. He became a touring actor, took a job as a tax inspector in Sussex in 1922, and then rejoined the RAF, and served in India for two years. Returning to England, he took a job with the relatively new British Broadcasting Corporation, in 1925, and hue stayed there until retirement in 1956. He was a founder of the new genre of radio drama, producing around 200 plays, and in 1930 he produced the very first television drama, which was Luigi Pirandello’s 
The Man with a Flower in his Mouth. The main character was played by Val Gielgud; the sets were painted by C.R.W. Nevinson. Here are two pictures of Sieveking with Gielgud; in one Sieveking is lowering a “fade board”, which, by hiding Gielgud’s face, enabled the production to move from one scene to another.
Although he had been significant in the early days of broadcasting, he never achieved success in television. In 1938-39 the BBC seconded him to work with the Canadian Broadcasting Corporation. He then moved to BBC Bristol, and from 1942 to 1944 was regional programme director for the western region. He disliked administration, and from 1944 until his retirement in 1956 he held the job of drama script editor.
He was married three times: from 1924 to 1928, from 1929 to 1939, and finally in 1949. In his book of reminiscences, The Eye of the Beholder, published by Hulton Press in 1957, the year after his retirement, he noted:
When I was a boy some people used to shake their heads gravely when the then Duke of Westminster was mentioned, because he had remarried a number of times. I accepted without question the view that he was, to say the least, not a good man. I am not so sure now. In the light of my own experience, I should guess that he was a pretty average nice fellow, but . . . well—unlucky (11).
Interestingly, his reminiscences were almost entirely about his encounters with people who had influenced him or intrigued him: several of them in the pages of this website, including Chesterton, Shaw, Kingsmill, Sitwell and Wells.
Sieveking’s books include several works of science fiction. He published a short story in 1922, about a time viewer, called “The Prophetic Camera”, and his first novel Stampede! (1924) which was dedicated to and illustrated and inspired by, G.K. Chesterton, featured a 
thought machine which anarchists used to issue telepathic commands. In The Ultimate Island: A Strange Adventure (1925) Atlantis is rediscovered behind whirlpools and fogs, which have lured ships to their fate for centuries. All Children Must Be Paid For (1929) is a science-fictional satire on eugenics. He is probably best known for A Private Volcano: A Modern Novel of Science and Imagination (1955), written for Ward Lock’s “Modern Novels of Science and Imagination”, of which he was editor in 1955 and 1956; it featured a volcano which threw up a catalyst converting all dross to gold.
For details about the science fiction, I am dependent on John Clute’s piece in the Encyclopedia of Science Fiction. For details about Sieveking’s life I rely on the Oxford Dictionary of National Biography entry by C.A. Siepmann. The pictures from his BBC career come from a webpage about the early history of television.
Science Fiction and Fantasy Writers in the Great War 