Identification Required

Saw this bird a couple of years ago while walking along the riverside. Wasn't sure what it was at the time but forgot about it once the photo was loaded onto my laptop. Going through the photos I have collected over the years, deleting the unwanted ones, moving others to selected folders and making up slideshows.
Still not 100% sure what the bird in the photo is. My first thought was a female Reed Bunting. There are plenty of males in the area but what I assume to be the female was always in the thick of the bushes and not easy to see or photograph. This may be the first female I have seen in an open setting. Can anyone out there confirm the identify of the bird in the photo? Sorry no prize to whoever identifies it. Many thanks.