QUOTE(Ms.Fiddle @ Feb 20 2009, 11:11 AM)

Aker Bilk's vibrato isn't widely admired as far as I know, it's a bit much for my taste.
It is a very wide vibrato - and probably not what you should, as a general rule, aim for.
There are two types of vibrato : diaphragm and jaw. I much prefer using the diaphragm for clarinet, gently pulsing it. Do it really slowly to start with, practice a LOT, and eventually you'll get the control you desire.
I wouldn't use it though in a great deal of 'classical' stuff at all. In jazz, I'll add a small amount to add some colour to the tone.