By George, I think he's got it. Thanks Dave.

I don't know how that happened - I know I've never intentionally set it to private browsing.

I had a feeling it might turn out to be something simple.

You'd think there'd be some indication in settings as to whether the browser is set to Private or not. There's a note in there about the facility, but nothing to indicate you're in it or not. Just a mention of a slightly darkened scree, which I would never notice, because I often turn the brightness down to save the battery.