Thing is, these cars are virtually un-steal-able these days, unless you get car jacked or they break into your house to get your keys.
In the first instance, this would have to happen to you in a car park, unless you turn off the auto lock over 15 mph feature, and you really don't want it to be returned to you after it's been ragged around by some muppet, and in the second if your car keys weren't secured in a safe or something, a number of insurance companies won't pay out.
Thankfully the majority of UK insurers don't insist you have to have trackers on cars of this value.