About 7pm tonight. It will be a passage bird and will have moved on tomorrow. I've never seen one as they call from deep cover, usually in scrub, and afternoons and evening seems to be their time. However a birder friend of mine says they will call in the middle of the night. Only thing you can confuse them with is a grasshopper, and they are considerably louder than any insect.
Blackbird calls pretty late too, and robin - usually one of the first to call in the day, often before sunrise. Starlings will set up a noise if you disturb their roost.
Nightjars aren't really songbirds, but they do make a great noise! Spooked me the first time I heard it, especially when they do a wing clap as well.
Weirdest noise of all though is manx shearwater. Have a listen if you can find a recording, then imagine 10,000 of them all at once. I stayed for a week on Skomer island, and the sound was indescribable after dark.
