My experience of travel suggests to me that honking is cultural: what's normal for Mumbai doesn't happen in London.

In the UK, the horn might be used to "wake up" a driver in front - e.g. the traffic light has gone green, the driver in front isn't paying attention, so the car behind might sound a short honk to alert the driver in front that the light has changed. There's also the annoyed "you cut in front of me" / "you did something dangerous" long blaring honk.

Those are the two main accepted uses of the horn in the UK, so there isn't much honking in UK traffic jams.