Green’s Dictionary of Slang

es-roph n.

a horse.

1859		Hotten Dict. of Modern Sl. etc. 126: es-roph, or es-roch, a horse.
1864, 1867, 1870		Hotten Sl. Dict. [as cit. 1859].
1873		Sl. Dict.
1891		Exeter & Plymouth Gaz. 15 Oct. 6/4: Stow yer gaff, the es roche (horse) was mine.