Green’s Dictionary of Slang

amesjay n.

[backsl. = james n. (3)]

a sovereign.

[UK]Sporting Times 4 Sept. 5/3: George Fredericks estimates the damage in glass at about four spangles and half an ames-jay,.
[UK]J.B. Booth Sporting Times 21 Aug. 1/2: I’d ’ardly got a touch-me in my sky, much less an amesjay to pay for me saint an’ sinner!