This is the Lamplighter.
He walks through London's streets every night, lighting the lamps. As the new day arrives, his black, sweeping coat snuffs them out again. You know he's recently been through your street in the morning if there is a thick mist hanging low over the cobbled ground.
No one knows where he came from, or where he lives. He will politely decline to answer if you ask him. He's just there. Every night.
Ahem. Just an experiment, really.