Like most industries, the car business awards itself a large holiday over Christmas and New Year.

So every year I park the moderns and spend a fortnight chuntering around in my 30-year-old Series III Land Rover (below). This is no self-flagellating ritual to purge my soul of all the automotive excesses of the year but simple common sense: for the last three winters there have been times where no modern car on normal tyres would have got through the snow, while this year the winds have knocked down enough timber around here for me to have spent most of my spare time in the fields felling, sawing, chopping and storing. I’d love to see what the inside of a modern Range Rover would look like after a fortnight of that.

But this year more than most I have been thinking about the car that must, in time, replace the much loved Land Rover, be it a leaf-sprung car like mine or the be-coiled Defender of more recent years.

Land Rover has got so much right in recent years. It has figured correctly that what matters most is not that you produce the best car in the class, but merely the most desirable. The Range Rover and Discovery are excellent examples but none illustrates the point better than the Range Rover Sport (below).

By some margin this is the worst car Land Rover makes, yet it has been an outstanding success because its creators knew its brutish get-out-of-my-way appearance would find favour among the more unreconstructed elements of the community. Basing the car on the Discovery but charging far more for it clearly helped too.

The new Evoque (above) adheres closely to this theme. With its cramped rear quarters, average engines, letter-box rear screen and ergonomically flawed driving environment it is an easy car to fault, but do I think any of this will stand the way of its success in the showroom? Clearly not, any more than will the huge prices Land Rover is asking for them: it shares its platform with the Freelander but because it’s badged as a Range Rover and looks the way it does, prices start fully £6000 further up the scale. And queues are forming.

So it seems that in all things Land-Rover perception is more important than reality. The irony of function being made to follow form in this, the company that built its brand on practical values, will be lost on no-one.

So will it work with the new Defender (below, as a concept)? The Freelander underpinnings are about the right size and with some squared off bodywork the right kind of look could undoubtedly be achieved.

And it would be a disaster. The only reason Land Rover has been able to sell all those Range Rover Sports and Evoques is that, underpinning it all, is an authenticity the brand has carried since birth, the authenticity provided by the original Land Rover. In exactly the same way, it was the 911 that allowed Porsche not only to get away with but also to make such an outstanding success of the Cayenne.

So Land Rover has to accept that the Defender will be expensive to build, because it can’t be based on anything else. It should have a ladder chassis, because then there is no limit to the amount of different bodies it will accept, and an interior you can quite literally take a hose-pipe to. It must be without question the best off-roader in the market, with approach and departure angles that are unbeatable, just as those of my ancient Series III are to this day. It must be able to be repaired easily and anywhere, by anyone with only basic mechanical skills and tools.

The bad news is that it won’t make as much money as a repurposed Freelander, at least not in the short term. But over time, the rewards it will bring Land Rover as a company, in providing more bedrock upon which the brand can grow further, mean that its contribution will be incalculable. Land Rover will enter its 65^th year in 2012, and that original design – albeit somewhat evolved – is still out there despite the approaching pension. The rewards of making the next Land Rover a truly authentic car worthy of this heritage may take time to arrive, but when they do it’s hard to imagine anyone saying that the extra effort and expense were not worth it.