Decision Height

[mjrhealth]

First off most UK landing videos seem to leave it as Zero, but question is, is it supposed to give you an audible warning or just the flashing DH on the Screen

[N1K]

Flashing DH and there is a light on the altimeter. 
I set it to 20 for a 'flare now idiot' warning on night approaches when you get the whole black hole effect.