Here is a second young Robin from in the garden, I think this is from a slightly earlier brood than the one in my main album. As you can see his plumage looks nearly like an adult Robins. He is just waiting for the last few feathers on his head to grow out.
Another difference is that his red breast is much fuller, and does not appear to have a central white v.
So I think this one is more likely to be a male.