I heard it this morning when I was hanging out my washing - the first cuckoo of the summer. I had a little 'run' around my patio because if you don't run when you hear the first cuckoo, you'll be lazy for the rest of the season! I don't want that to happen, I'd never get anything done.
I don't have a photo of a cuckoo, I'm not sure I've ever seen one, so the photo is Cuckoo-pint which is just appearing in the hedgerows now. Its also called Lords and Ladies depending what part of the country you are from.
Enjoy the lovely summery weather.