This whole thing is totally deranged.
I *do* have a One Login account with this email address (entertainingly I personally have *TWO* "One Login" accounts)... but read that carefully: "[...] for HMRC".
... and keep reading: "If you use GOV.UK One Login elsewhere [...] you cannot use it for HMRC yet."
Which means this is either strange for just-me, or it's a global "not for HMRC yet". If it's the latter, why did they even offer it as a login method?!
