At the Goodwood Festival of Speed last weekend it would have been easy to spend the whole day milling around the paddocks and classic displays and to have ignored the new car displays, but I’m glad I didn’t because Land Rover had one of the most interesting show stands I’ve seen in years.

The company had splashed the cash and built a very mock production line that showed the Discovery being assembled. What was really fascinating was the fact that the Discovery’s unusual T5 architecture had finally been laid bare.

When the T5-based Disco 3 was launched in 2004, much was made of the car’s substantial 2.5-tonne weight. This was a result of the T5’s belt and braces approach, using both a separate chassis and a structural monocoque body.

The Goodwood display made crystal clear the reasons for the Disco’s immense off-road ability. The huge longitudinal chassis legs that run from front to back and the massive subframes give the Discovery’s suspension the ultra-rigid base it needs to work properly in extreme conditions. You won’t have full confidence in off-road conditions if the wheel control is compromised by chassis flex.

The decision to also use a structurally very strong body on top of this high-tech structural ‘ladder’ is not surprising when you consider that work began on the T5 around the turn of the century and not long after the Ford Explorer scandal in the US. A combination of too-low tyre pressures in compromised tyre design too often combined to cause sudden blow-outs. This caused the Explorers - tall vehicles with unsophisticated chassis designs - to flip. The resulting impact would cause the roof pillars - which were not structural - to collapse often with fatal results.

All of which makes perfect sense when building a really serious off-roader. The serious downside is the weight and the consequent impact on fuel economy which, since the T5 architecture was conceived, become of vital importance in all global markets. And there’s another, in-house, reason why the T5 will start looking even more out of step with real-world motoring. Not too far into the future, Land Rover will unveil the new all-aluminium Range Rover.

This is expected to weigh in at around 2000kg, about the same as the Porsche Cayenne and a good 450kg lighter than the Discovery. The all-new Range Rover Sport, also based on the new aluminium chassis, is also not too far away. Which is why this clever display at Goodwood showed such foresight on the part of Land Rover.

With its lightweight sister cars on the horizon, the company is moving to re-position the Discovery as a proper trans-continental all-terrain vehicle and away from its previous role as a kind of over-sized family car for the affluent. Indeed, the Disco that recently spent 50 days driving from Birmingham to Beijing was also at Goodwood, underlining the car’s extraordinary ability.

So when the new, more metropolitan and more executive-biased Range Rovers appear and people asked Land Rover why the Discovery is so heavy, the company’s answer will be simple: because this is our ultimate off-roader.