V late Last night. Started as if someone was pressing the horn repeatedly and then went on non-stop for 20 odd minutes. Police were called and lots of chatter. Annoying yet intriguing. Can anyone shed light?

One should only use the Horn to warn moving vehicles that there is a danger.
Let us hope the Police arrested them

Much worse was an ambulance blaring its siren in an empty Honor Oak Road at approx 0245 this morning. Why do they do it? Perhaps the driver had the perverse pleasure in waking up all the sleepers in HOR?

Some car alarms work by repeatedly sounding the horn. I think this is more likely that someone sitting in their car hitting the horn for twenty minutes.

When you say in the road sirens blaring, do you mean stationary or passing through?
If it was moving, then they are still required to use their sirens even on an empty road, approaching corners, junctions and crossings.
I'm sure it would have been more annoying first hearing a smash, then 20 mins of EMS vehicles turning up on the scene, engines revving running pumps and hydraulics etc.

Apparently a car alarm went off after someone smashed a window in it. The owners couldn't stop it and neither could the police.

But that info is a bit third hand.....

Disconnecting the battery usually always works

Not necessarily - many alarms have their own batteries.

Arrest them? That's a bit extreme isn't it? Surely a ticket or words of advice would be more appropriate?

That's a bit insulting towards our members of the emergency services isn't it? I imagine the driver was on an emergency call..... the sirens are to warn other drivers of the presence of the ambulance: at night people driver faster and more aggressively. It is important to warn other drivers of presence especially when you can't see them - like maybe around corners.

Or maybe we should stop ambulances making progress - and prohibit them from using their warning equipment. Let's just hope you don't need them in a hurry if you're having a heart attack.

I did say USUALLY and the chances are if its sounding the car horn as opposed to a siren its running off the car battery