I've just spoken to a neightbour. It's water works to do with another street. But they've been here all weekend and all day today without actually doing anything. Starting this time of night is ridiculous.
This happened to me recently. Myself and at least several other people called the water board about an issue in the morning. They spent the whole day in the street. Turned the water off at 12 (no warning or knocking on doors, not a huge street either) started digging the road up between 6 and 7pm. Finished around midnight. Baffled me.