Nice video there Jay, and easy to understand too.
I can't find what Landy Peter has, but it's worth noting for his benefit that all Land Rovers after the last series are permanent 4 wheel drive using the centre diff principle unless it was a special build or modified later by an owner.
Depending on which model he has, the centre diff may or may not be a lockable differential, especially on some Discovery models when the only options on the transfer box are 4WD high ratio, 4WD low ratio or neutral. Models without a locking centre diff often have electronic traction control installed in an effort to limit wheel spin.