Thanks Guys - I got some great shots that day I think a combination of newly arrived Swallows, House Martins and Sand Martins all desperate to feed after a long flight and the weather conditions which combined a rainy day with very low cloud and a strong headwind blowing laterally down the flash made conditions favourable to get the photos. I have a number of shots of swallows perching on a branch over the water too which I've never seen before - poor little sods were exhausted.
I saw the same thing once before about a year ago in a wetlands north of Sydney. Unfortunately it was a rainy day and the light was coming from the wrong direction so the pics weren't the best. Saw several birds resting on stags (that's the dead trees, not the deer) too.
