There are lots of iPhone users on the Islington forum and some had problems because of cookie settings.
Edit: looked through your comments, the logging out thing is related to cookies. Have you tried changing to "Never" block cookies: support.apple.com/kb/TS4207 ?
If you have, it could well be a bug in Persona or how we've integrated it, so any more detail is helpful.
Ok, I have made the change to "never", and will report back.
You + Technology never works. I'm surprised you can even login.
Well as long as it's just me then that's fine I guess, it might be a problem if it affected everyone else who has an iPhone, or even a significant proportion of them.
It didn't work, logged me out again.