I've got the Colossus ground anchor set into concrete. It's a flush fit, so you can't trip over it. I got mine from Peak Motorcycle Security (highly recommended), who came down from Leicester to London to fit it, though you might be able to fit it yourself.
Take a look at these:
http://www.bikesecure.co.uk/acatalog/Anchors.html
http://www.elitesecuritysupplies.com/ground_anchors.htm