There are still a few of these birds locally that have not paired up yet and are singing for a mate. This is usually the only time you can get a clear shot of them as they spend most of the time lurking in deep vegetation. This bird kept returning to the same bullrush stem, in seed, to sing.
Taken with 1D MK3 and 500 mm lens handheld at ISO 125 F7.1, -0.67EV, 1/1250s and evaluative metering
Good of you for recognizing the opportunity and taking advantage of it. Good singing pose, and I like that you left some space for the tip of the bullrush.
Many thanks for your comments Axel, Daniel and Judy. I noticed when I was going through the photos at home that the bird was ringed (lower leg on this photo). I live in an area where a large amount of bird ringing is undertaken and tend to generally find that birds that have been ringed are much less bothered by human presence than those that have not been.