Emperor Dragonfly

My wife spotted this on a plant in our front garden this afternoon. Just had time to grab the camera and get a few shots before it moved off. Not sure what it was doing there as I always thought they hung about near large, well vegetated ponds and lakes. The only water near my house (apart from a bird bath) is a small pond in a neighbours garden a couple of hundred meters away! To be honest, it seemed a bit sluggish, but it flew away OK!