So, we are on holiday in Wales went for a stroll to the Henrhyd waterfall, that you can walk behind...anyroadup on the way to the falls following the river we saw three or four birds, very Swallow/Swift like, flying fast about a foot above the water, probably feeding on insects, but in the dappled light they were a very vivid, iridescent, dark purple on their backs, any idea what they were please?
