Baby bird

On Thursday I went outside to water our garden and noticed a bird fly away quickly and some movement & noise where the bird had been. When I got a little closer I noticed that there was a baby bird sitting there in the corner of the garden. It was not a really young baby because it had a lot of feathers already and looked a little "plump". I have no idea where it can from because there are no trees nearby that could house a bird nest. I watched throughout the day and saw the mother bird (a Robin) numerous times flying down to feed the baby. A little later on it had moved to the other side of the garden gate so it was in the front yard and then a little later it was back where I had first seen it. On Friday it had moved to another corner of the garden and I haven't seen it today at all. I hope that it is still alive and that it was able to fly away at last...