Definition of "diego"

They're just like Ludds, them diegos — nothing but a load of scum. I've seen 'ow they live. O' course, we soldiers dwell in mud 'alf the time, but that's different. We're building an empire. But them diegos! Them Jimmies! Well, I tell you!

1987, Glyn Hughes, The Rape of the Rose, page 177

"... Around twenty years old and pretty tall for a diego, maybe five-seven or five-eight." / "A diego?" Armand said. "He's a diego?" / "From Napoli."

1985, Robert Anton Wilson, The Widow's Son (The Historical Illuminatus Chronicles), page 17

Now I don't know what it is with the diegos, but as we were walking back to the hotel a couple of them started giving us a bit of verbals.

2009, Mickey Smith, For The Claret & Blue