Sorry Scrump to be pedantic, but. Looking at the other thread, Chas's should have read Chas' (shades of a Lizzie) Bit like the Mornigton Cresent game this, ain't it?

Chas

Well, I wouldn't want to argue with you on that point, Chas, although my understanding is that (apart from your particular case), either Chas' or Chas's is correct.

And if you are being pedantic, the least you could do is spell "Mornington Crescent" correctly ;-)