Be careful if the car already has such a switch some circuits by pass it like the clock & power to the ECU.
ECUs can loose their settings if power is removed.
Juuuuuuuust remove the plywood parcel shelf & you can se if it is bypased
Hmmh, the battery switch has been installed by a well known Morgan Garage and it works perfectly. And I have no clock... But thanks for your comment. I will check whether or not it is bypassed.