Going through the family archives I came across several bits of information that suddenly came together. My grandfather’s cousin, Frederic Whyte, appears to have been a writer of some note. His books include:

Actors of the Century: a Play-Lover’s Gleanings From Theatrical Annals (1898):
The Life of W.T. Stead (1925, two volumes) – was reprinted as recently as 1971, a much-cited biography of the crusading English journalist who was drowned on the Titanic
William Heinemann: A Memoir (1928) – also seems to be fairly well known by those studying the publisher and his circle
A Wayfarer in Sweden (1930): “Travellers in Sweden will find this a useful reference book with aninteresting look at various areas of the country. It has hints, tips for travelling, and some history and information about the different areas that can be visited”
[with A. Hilliard Atteridge and Harold Wesley Hall] A history of the Queen’s Bays (The 2nd Dragoon Guards), 1685-1929 (1930)
A Bachelor’s London: Memories of the Day Before Yesterday 1889-1914 (1931): “Memories of literary London – stories of publishers and authors before the first world war”; “A wonderful evocation of literary London at the turn of the century”

He also translated and edited:

The English Stage: Being an Account of the Victorian Drama, by Augustin Filon (1898)
Flashlights in the Jungle A Record of Hunting Adventures and of Studies in Wild Life in Equatorial East Africa, by C.G. Schillings (1906) (vt In Wildest Africa, With Flashlight and Rifle)
Grip and I: Our Adventures in Nigeria, by Count Crondstedt (1924)
A Field-Marshal’s Memoirs: From the Diary, Correspondence and Reminiscences of Alfred, Count Von Waldersee, Moltke’s Successor as Chief of the General Staff of the German Army, 1888-1891; Commander-in-Chief of the Allied Forces in China, 1900-1901. (1924)
The Life of Benito Mussolini, by Margherita Grassini Sarfatti (1925)
Letters of Prince Von Bulow – a Selection from Prince Von Bulow’s Official Correspondence as Imperial Chancellor during the Years 1903 – 1909, Including Many Confidential Letters Between Him and the emperor (c. 1930)
These Moderns: Some Parisian Close-Ups, by F. Ribadeau Dumas (1932)
Sport & Exploration in the Far East – a Naturalists Experiences in & Around the Kurile Islands, by Sten Bergman (1933)

His papers can be found in Newcastle University Library.

Frederic’s precise relationship with my family is a bit complex. His father, Henry Whyte, was the son of an Edward Whyte who was the brother of my great-great-grandfather, Nicholas Whyte. So that would make him (clickety-click) my second cousin, twice removed. But his aunt Catherine Whyte married a bloke called George Ryan, and their daughter Caroline then married my great-grandfather, Nicholas Whyte’s son John Joseph Whyte, and became my great-grandmother. So by that route, he was my first cousin three times removed.

Judging from my grandmother’s diary, our branch of the family was on good terms with Frederic’s elder brother Jack, who had no children. Frederic married a woman from Jonköping and moved to Sweden (several of his books are translations from the Swedish); his son Henry was born in 1917 and died in the early 1990s, and we stayed very vaguely in touch through Henry’s wife Ingrid – indeed my sister and I actually met up with her in Stockholm in the summer of 1990, with no idea of her father-in-law’s literary career (she and Henry had no children, so that is the end of that branch of the family). I shall keep an eye out for Frederic’s books now.