Twitter broadcast a Little Gull at Amwell. I'd just arrived to observe it when a Marsh Harrier was called flying high over. The cream crown did a leisurely circuit then moved on toward Rye Meads. Meanwhile the adult Little Gull dropped into the Reeds by the viewpoint, before doing some fishing then flying off high south.
Other birds were the first House Martin of the year for me, Swallow, Sparrowhawk, Redshank, Snipe, Little Egret.