As the bike is kept in a Garage a couple of streets away from where I live, I spent today beefing up the security. After burning through 2 batteries in my battery powered drill trying to drill into concrete. I admitted defeat, and had to use a generator, and a proper hammer drill, so I could drill the 16mm holes needed for the ground anchor.
I've purchased a 2 meter long chain, which loops through the ground anchor, and over the top of the engine, through the frame. Anyone who wants to steal this bike is going to have to try very hard.
The chain is 16mm! It weighs a ton, and each link is nearly the size of my iphone. I've taken a picture of it next to my RE key, so you can see how big it is. I've quite impressed myself with its lack of subtlety.