What can I do about this?

[JackieBauer]

Someone has parked their car directly opposite my house and the car alarm is going off. I have family coming for dinner and it's going to drive everyone nuts. Never seen the car in the street before

Start knocking on neighbours doors to see if it belongs to a visitor? Maybe they can't hear it/don't realise it's their car.

Car battery won't last till lunch time and then it will stop! Sorry that's not very helpful is it?! Call local police station if it's still going off on an hour? They'll be able to find out who it belongs to....

Call the police, they might be able to get it towed away.

They usually stop after 20 minutes I think

Thankfully it's stopped, Merry Christmas

Ah, the power of MN!