Flo single monitor arm by colebrook bosson saunders.
Here's the blurb from the creators:
"As the market leader in its class, Flo is more environmentally friendly, better looking, and a better performing product than any of its competitors. With great design and great performance, Flo offers a range and ease of movement that sets it apart from all other monitor supports."
and here's what I say:
These monitor arms are blimmin nice! They have a fantastically smooth range of movement, look great and can take just about any size monitor (including touchscreens!!)