Hi Evil Tony, firstly thanks for pointing out my typo, of course I meant 'unches' but, as I've said before on here, I still type with none finger and the eyesight isn't what it once was.
Regards "Nina", it refers to a crossword setter or caricaturist who used to always hide his daughter's name 'Nina' in his drawings.
This explains it better:-
Why is it called a Nina?
Many think "Nina" is an acronym. It isn't.
The word comes from Al Hirschfeld (1903-2003), American caricaturist, who was famous for hiding his daughter's name "Nina" into his drawings. Wikipedia says:
The name would appear in a sleeve, in a hairdo, or somewhere in the background. Sometimes "Nina" would show up more than once and Hirschfeld would helpfully add a number next to his signature, to let people know how many times her name would appear.
Hirschfeld's artwork is here, I've strained my eyes trying to spot Ninas in the online images. Can you see any? He started the trend in 1945, the year his daughter was born, so look for artwork created post-1945.
Crossword setters then brought Ninas into the realm of crosswords. If you happen to know which publication/setter started the trend, do write a comment about it.
Update (24-Mar-2011): Thanks to Peter Biddlecombe for sharing with me what is possibly the oldest Nina, from the Times crossword of July 1967. Nowadays Ninas occur quite often in the Independent crossword, and occasionally in the Guardian and FT. I haven't yet come across one in the Times, or in any of the Indian crosswords.