Having thought that our wrens had decamped to another nest site, I now think that we have two pairs of wrens in the garden. I also think that they are feeding young as they are making fast return trips to the nest sites with food.
The two pictures were taken a fifth or a second apart as the bird turned on a branch and flew off. Notice how the left foot is turned outwards.
Another innovation is our window feeder on the conservatory window, just 18 inches from the wrens nest box. This feeder is loaded with fat nibblers and dried meal worms. It attracts lots of sparrows, starlings and blackbirds.
Now that they are used to the feeder, they will feed even when we are sitting near the window. We know when the feeder is in use, as the birds beaks bounce on the plastic (dit-dit-dit), and I can usually tell the type of bird feeding from the noise.