Green’s Dictionary of Slang

neddy n.1

1. [mid-17C–1960s] (also Ned) a donkey.

2. [early 19C+] a fool, a simpleton.

3. [late 19C+] (also neddie) a horse, esp. a racehorse.

In phrases

the neddies (n.)

[20C+] (Aus.) the sport of horseracing.