I just coated mine with a couple of layers of Future floor polish.
*edit* I have heard you can get Future in the UK under the brand name Klear
If there aren't any scratches in the grips, it should wrk just fine for you too.
Using a Q-tip to apply it, I did the grip side first, covered it with a piece of Glad-ware to avoid dust ruining the finish, and let it dry over the course of a couple of days. The Future is very self-leveling so it won't pool up and I've never had a problem with bubbles on the surface, etc.
When it was completely dry, I flipped it and did the back side in the same manner.
When dry, the Future still retains that "wet slick" look and is great.
I'll try and get a picture up in this post shortly to show you what it can look like.
*edit* Here's a pic of the finished product:
Bruce