Green’s Dictionary of Slang

John Bull n.1

also Bull, Bully, Jack Bull, Jacky Bull, J.B., Johnnie Bull, Johnny Bull, Miss Bull
[first used to name a character in John Arbuthnot’s The History of John Bull (1712), in which he also coined Nic Frog + Louis Baboon, for the Dutch- and Frenchman respectively]

1. [early 18C+] an Englishman, the British, Great Britain; an English ship; thus John Bull-land, England/Britain; see also (1846) Lady Bull, an Englishwoman; also attrib.

2. [mid-19C-1900s] an English woman.

3. [1910s] (US short-order) a beefsteak.

In derivatives

John Bullism (n.) (also Johnny Bullism)

[19C] self-conscious promotion of the stereotyped characteristics of a ‘true’ Englishman.

John Bullish (adj.)

[1910s] agressively patriotic.

John Bull-ite (n.)

[mid-19C] an Englishman.

In compounds

John Bull’s bastard (n.)

[1940s–50s] (Irish) an Englishman.