This thread is a decade old but I found it when googling details about Robins singing up close to you and thought I’d see if anyone else has found the same.
Our usual Robin hasn’t got a mate this year. He takes mealworms from our hand but eats them straight away, so hasn’t got a family to feed. If we’re in the garden, even after he’s had mealworms, he settles close and sings fluffed up and moving his head from side to side almost as if he’s singing to a mate. Maybe he’s just a lonely old frustrated Robin but it would be good to know if anyone else has had this experience.