Imo a layered approach works best. Find out how landrovers are broken into, how the security is defeated and go from there.
To start with upgrade the std security , with a little imagination it isnt hard.
All the info is on the internet and im not going to out it on a public forum telling people how to nick them and what additional measures i have made bar the obvious. Sorry. I live in the middle of Liverpool and mine lasted 10 days before the 1st theift attempt, since i got the proximity alarm and trained the dogs to react its been left alone.
but the things you can see on mine are rear window security bars, a disklok with the welded bars to prevent it from being peeled off or jacked apart, a pedal lock and padlocks and chains between doors that are not in use. I also have a second alarm and imobiliser with a proximity alarm that starts warning you away if you get within 2 foot of it.