On a second quick visit one evening when returning home down the A1, I found a very good area for photographing where the bird perched to sing very much in the open. The evening light was beautiful but did create a harsh shadow across the tail so another visit was required!
By the next visit a few days later, the number of singing birds had diminshed and they were singing less often but I did manage a sharp image in mottled sunlight.
The final (?) visit yesterday to the same area produced some wonderful views - still not perfect as there are branches across the tail in one and a rather bland background in the other. Perhaps another visit is required - so photography becomes an excuse to return several times and experience the wonderful song of this amazing bird.