In article ,
am says...
Minoura spacegrip. Can be found at wiggle, LBS in some cases, other
online places. Comes in two sizes.

Great - will investigate. Thanks.

They have a groove in the bottom of the bar to allow side-to-side
movement. Once you have chosen the position, I would suggest putting a
small piece of electrical tape over this hole as it can produce an
amazingly irritating whistle when riding!

Jon