Alfred George de Glehn (1848 – 8 June 1936) was a notable English-born French designer of steam locomotives, and an engineer at the Société Alsacienne de Constructions Mécaniques (SACM). His steam engines of the 1890s combined elegance, high speed and efficiency. De Glehn express locomotives were first used on the Nord Railway, and on the boat trains from Calais to Paris where they impressed passengers with their speed.
He invented the de Glehn system of compounding, and de Glehn types were built in large numbers in France, and some were also built in Belgium, Germany and New Zealand, see Compound locomotive. Compounding lost favour from the 1900s, being replaced by superheating. However André Chapelon rebuilt many of the French de Glehn compounds from 1929 onwards.
He died at his home at Mülhouse in Alsace at the age of 88. The house had been commandeered as the German district headquarters in World War I. He had changed his surname from von Glehn when he settled in France.
He was one of 12 children of Robert von Glehn from the Baltic provinces with estates near Tallinn in Estonia, who had settled in England and married a Scotswoman. Their home in Sydenham, London was the rendezvous of artistic, literary and musical people: George Grove, Arthur Sullivan, Jenny Lind and J. R. Green.
Louise Creighton a British author and activist was his sister. A brother Alexander von Glehn was a coffee-merchant and built narrow-gauge railways in France. Alexander was treasurer of the Protestant Evangelical Society of Relief in Paris which provided help to victims of the Franco-Prussian War. Alexander’s son Wilfrid de Glehn was a British painter. The family in England changed their surname from von Glehn to de Glehn in 1917.