Little Brown Job

I really ought to know more birds (yeah, I know) but I think this is some variety of warbler? It flitted from reed to stem to branch as I wandered along the side of the River Severn today. I was hoping to catch some river marginals, but all I got was a handful of seagulls and a few ducks. The light was dreadful and none of the in flight gulls were really that good. Still, it was a nice walk and there's always another day.