No one or no one

[stackdump]

What is the deal with the hypgen in the word "no-one". If I look at

http://www.freesearch.co.uk/dictionary/no one

it states;

no one
pronoun (ALSO nobody)
no person:
- At first I thought there was no one in the room.
- "Who was that on the phone?" "No one you would know."
- I'd like to go to the concert but no one else (= no other person) wants to.
- No-one told me she was ill.

Why does the last example have a hyphen?, or is it optional in all cases?
.

 

[ascotta]

Erm confession, I used to have a horrible problem with this word/set of words, same as I had with spelling business (buisness) nobody seemed to correct it when I used noone, yet it just looked like noon-y to me and it always just looked wrong. I am lazy so splitting the word was a bit too much effort. I now to avoid embarrasment either totally avoid it, or use nobody.

[blue] A perspective from the other side!![/blue]

Cheers
Scott