Green’s Dictionary of Slang

1. a cat [the supposed story of a sailor who came home after his first voyage unable to remember the name of a cat and asked his mother ‘What’s she called, that ’ere long-tailed beggar?’].

[1834		Marryat Peter Simple (1911) 10: You must larn to chaw baccy, drink grog, and call the cat a beggar].
1864, 1867, 1870		Hotten Sl. Dict.
1873		Sl. Dict.

2. a large denomination sterling note [long-tailed ’un n.].

1923

J. Manchon Le Slang.