At school I was taught to write: realise, orginise, compromise - now I find it: realize, orginize and compromize. My memory's gone wrong, or did something change which I missed?
Chris is correct. I would also point out that the BBC uses the Z version though. They use the first version that appears in the Collins Dictionary, and they list it: Organize, Organise.
I started primary (11+) school at Escola Britanica in Sao Paulo and finished secondary education at Terra Santa College in Cyprus. As far as I can recall, it was always "realise, orginise," etc.
I did of course speak with the Yankees, but it was rather hard to guess whether they were pronouncing the "z" from a written "z" or a "s".
Thanks for the hint, Chris! I had an irksome feeling that them Yankees had somethin' to do with it, though!
When you said "...but it was rather hard to guess whether they were pronouncing the "z" from a written "z" or a "s"", it made me think that I should point out that, even though, in the UK, they spell these words with an "s", I'm pretty sure that they, like the Americans, also pronounce them with a /z/ sound.
So I suppose even if you didn't have that problem, it wouldn't have helped you anyway! Oh well!