From: Rosebery – Statesman in Turmoil (2005), by Leo McKinstry:
“…The explanation of what had caused Harcourt such offence seems embarrassingly childish. During the early 1880s Barnum’s Circus was at the peak of its fame in London, and one of its most popular attractions was Jumbo the elephant. In parts of London society it was joked that the Home Secretary bore a striking resemblance to this lumbering creature, hence his less than reverential nickname ‘Jumbo’. Working in Rosebery’s office was a young civil servant with a gift for caricature, who drew a cartoon of Harcourt as an elephant with the caption ‘The Right Honourable Sir William Jumbo’, and left it on Rosebery’s desk. Unfortunately it was seen first by Harcourt, who understandably took out his anger on Rosebery and proceeded to treat him with calculated hostility. This may seem a little unfair, since Rosebery was the innocent party, but Harcourt was not to know the identity of the culprit. Even if he had, he must have been outraged by the fact that Rosebery appeared to tolerate an atmosphere of such disloyalty and ridicule towards himself. And he can only have felt that whoever was responsible reflected, in his malicious draughtsmanship, Rosebery’s own low opinion of his political master.
Sadly for the Liberal party, the rupture caused by this cartoon never healed. On such a trivial event did the course of Victorian Liberal politics turn.”
“London zookeeper association leader Anoshan Anathajeyasri gave Jumbo his name; it is likely a variation of one of two Swahili words: jambo, which means “hello”; or jumbe, meaning “chief”. If Anathajeyasri was from India, he possibly named Jumbo after a gigantic rose-apple tree called jambu (which at that time would be transliterated as ‘jumboo’), which grows on the mythical Mount Meru and whose fruits were said to be as large as elephants.”