After a while the game started running slowly, so it was time to refresh. Logged out. Logged back in...
... and after a couple of minutes I was greeted with "Welcome new Settler", and was invited to select an Avatar and name.
It appears that the link between my island and my account has been lost !
I normally login via my Ubisoft account.
Support suggested that I log in via FB to access my game. Didn't work of course. Awaiting further response.
Details...
//removed - BB_Trafffer
I know a couple of players who have lost their high-level islands. Support failed them and they had to restart from scratch.
Fingers are crossed for a quick resolution........