Do you mean Roundabout of a small bit of land with water round it? (its an joke with a mate from Derbyshire / Midlands folk who are only people in UK / World to call roundabouts Islands!
Ah, much closer to home Allblade, I pass through this several times a week, the much maligned (correctly) but definitely close to manchester, Simister Island !!!!!! And sometimes I even kept going until I get here! But then I keep going so no one nicks my bike.
And there's this one in Ashton under Lyne! The imaginatively named Sainsburys Island. You're gonna have to cough this to your midlands mate, they've obviously infiltrated the GM highways dept !
You're right I should know better coming from the home of Roundabouts of Britain - a well know publication in these parts. See http://www.roundaboutsofbritain.com/ No one owning up to be the mystery knee downer?