Sorry to hear the news. I've also posted it on the Defender2 forum with a link back to here. See you've also posted it on Landyzone too.
Might also be worth alerting any LR clubs local to your area too.
Unfortunately, steering locks alone seem to offer very little protection against theft and even the best can be removed within a couple of minutes. All that said though, a decent steering lock, together with a decent pedal lock, security etching, aftermarket alarm etc, the way you park it etc all provide hurdles for the thief to overcome.
I really hope you get her back. Please have a browse around the different threads on here on security products if you get a chance.