There's this mention of a new livery in that thread:
"Looking again at the journals, the new NIR InterCity livery is mentioned as being introduced progressively in the Feb 1989 issue.
Turning back to the 111 Class, 113 is mentioned in the Oct 1989 journal as having been 'repainted in the new "InterCity" livery - a deep medium blue with yellow end panels and red buffer beams'."
I guess that's it, right? So do we have any idea when the last mk2s were repainted?