Had half an hour free today so I headed down to St Mary's to see if I could catch up with the Marsh Warbler that was floating about. On the way to the willows a local birder told me that it was still there singing and showing briefly, if time was given. Once I reached the North Willows I went round to the North Facing side and was immediately given views of the Marsh Warbler, feeding on the edge of the willows.
The differences between itself and a Reed Warbler could be seen straight away, the lack of the reddish colour to the lower back and rump, and the different duller olive colour of the overall body, with the light buff breast. I only heard the song briefly, although it alllowed for a positive identification, might have a trip down tomorrow if it's still present to hear its call.