IT'S built in Britain, driven all over the world and has a reputation of being the ultimate off-roader.

The Land Rover Defender has been around for more than 20 years and in many a way it's the closest you can get to the original Land Rover of 1948.

When it comes to styling little has changed but underneath the iconic model has been brought bang up to date with a new diesel engine that meets the latest emissions standards.

With a capacity of 2.2-litres it replaces the current 2.4-litre diesel and although it may be the smallest engine ever fitted to a Defender it has lost none of its abilities.

To prove the point we have just put the latest model through its paces on a gruelling off road course through the forests of the Duke of Roxburghe's estate on the Scottish Borders - at night!

In scenes similar to those from a recent Army recruitment campaign - but without the benefit of night-vision goggles - we spent two hours negotiating narrow tracks, many shin-deep in mud, steep ascents and descents, angled traverses and waded through water-filled hollows so deep the water level was above the headlamps.

Such conditions are a Land Rover's natural terrain and the latest Defender passed muster in no uncertain terms.

Although winch crews were on standby not once were they needed to assist as the Defender plugged its way through some of the stickiest conditions imaginable.

The convoy through the forest was made up of the latest Defender 90 short wheelbase and the larger 110 models and the new line up is priced as before, ranging from around £21,000 to £32,000.

In total there are 14 different body styles ranging from pick-ups to seven seaters and the vehicle we drove was a longer wheelbase 110 Station Wagon weighing in at the best part of three tonnes and priced from around £26,000.

Taking the weight and bulk into consideration its performance through the mud was even more impressive.

There is nothing prissy about a Defender - it is as utilitarian as they come, although our particular model was fitted with a so-called Comfort Pack which, at £1,650, includes air conditioning, electric windows and a CD player into which you can plug portable devices.

The instrumentation was updated a number of years ago with LED backlighting to make it easier to read and operate but the overbearing philosophy has been one of ‘don't mess if it's not necessary' and the Defender is good, old-fashioned and functional.

While Land Rover has pioneered electronic off-road aids such as Hill Descent Control and the Terrain Response system which automatically optimises traction depending on ground conditions, the Defender retains mechanical selection of low ratio gears and the often cantankerous ‘diff-lock' lever.

Yet with these engaged the Defender is nigh on unstoppable and the engine braking is immense. On the steepest of descents the vehicle can be left to its own devices - feet off in other words - to ‘walk' its way downhill.

The new engine is a development of the 2.2-litre diesel Land Rover uses in the Freelander and it has been set up to deliver the same power and torque as the previous 2.4 engine while increasing the top speed from 82 to 90mph.

It is also noticeably quieter which is mainly down to a new bonnet design. It's a six-speed manual and the gearing gives plenty of pull under all circumstances.

Average fuel economy is around 28mpg for the shorter wheelbase 90 but closer to 25 for the 110, which is unchanged. So are emissions at 266 and 295g/km respectively.

Off-road it is a champion but its on-road manners remain very heavy duty and the turning circle enormous.

The Defender is very much the Real McCoy of 4x4s and definitely not one built with the school run in mind.

It is the model which has set the standard for lightweight utility vehicles for more than half a century and Land Rover knows it will be a tough act to follow.

A concept codenamed the DC100 was unveiled at the recent Frankfurt Motor Show in two guises - one aimed more at the leisure market - and the company is now canvassing opinion from key global markets before making any decision about a possible Defender replacement.

What is certain is that Land Rover is on a roll.

Its Halewood factory on Merseyside is working flat out to meet demand for the stunning new Range Rover Evoque and the Freelander while at the Solihull plant - where the Defender is built alongside the Discovery, Range Rover and Range Rover Sport - 1,000 new jobs have just been announced taking the company's UK workforce up to almost 20,000.

As well as the new engine in the Defender, slight cosmetic changes are being made to the latest Discovery and Range Rovers with new grille and headlamp designs while the Range Rover Sport is also refreshed at the front and now comes with a power operated tailgate.