... a milk float!
For years, since moving here, I have been repeatedly plagued by a disturbing graunching noise in the middle of the night - somewhere in the vicinity of 2am. I had been blaming the neighbours for running some sort of washing-machine or dish-washer overnight which was echoing through the drain pipework somehow. But this week I happened to be out late at night (on a secret mission) not merely once but twice when the actual offender came past.
Electric motors are supposed to be quiet. This one is definitely not quiet. It has been dialled up to 11 instead (though possibly only when being reversed at high speed by a Top Gear style of milk-float driver). Also: I'm a delicate little flower with hyper-sensitive hearing, even when indoors behind double-glazing.