We have trouble explaining this, but perhaps it’s simply that a few influential British news organizations have collectively adopted the newer spelling, while most of the publishers of books and journals (including prestigious British scientific periodicals such as suffix does risk distracting non-American readers with what is (mistakenly) perceived to be a Americanism.
Whichever suffix you use, it is wise to use that one consistently throughout any given text.
[Guardian] I realise I will still have to lodge a tax return but what will happen if I get a job?
[Herald Sun] However, for the telco’s competitors, it’s a sobering realisation that the battlefields in the mobile sector have dramatically widened.
I've been put on an "anti-mason" [hit]list, along with others who dare to write anything unflattering against the brethren; I've had heated debates and arguments in public forums and message boards; and I've actually been threatened, both subtly and overtly.