Definition of "ikey"

My son, if you go to the races to battle with Ikey and Mo,Remember, it's seldom the pigeon can pick out the eye of the crow;

1906, Banjo Paterson, Wisdom of Hafiz

I meant to start from Barrhill, but I missed the train, and then I hung on to old Ikey-Mo, which made my alibi much better,

1931, Dorothy L Sayers, chapter 29, in The Five Red Herrings

Clara had always been ‘ikey’ – reserved and superior.

1913, D[avid] H[erbert] Lawrence, “chapter 10”, in Sons and Lovers, London: Duckworth & Co. […]

What Arthur Griffith said about the headpiece over the Freeman leader: a homerule sun rising up in the northwest from the laneway behind the bank of Ireland. He prolonged his pleased smile. Ikey touch that: homerule sun rising up in the northwest.

1922 February, James Joyce, Ulysses, Paris: Shakespeare and Company, […]