It’s rare for a celebrated designer to revisit one of their own creations. Rarer still for an independent company to do so with the blessing of a brand like Aston Martin.

But that’s precisely what’s happened with the Aston Martin Vanquish CALLUM 25 by R-Reforged.

The brainchild of design legend Ian Callum and Swiss-owned engineering company R-Reforged, it’s a fresh take on the Aston Martin V12 Vanquish that was in production from 2001 to 2007.

Callum penned the original design in the late 1990s. It’s perhaps his most iconic creation – one that took the svelte contours of the DB7 (another Callum classic) and infused them with steroids to create a shape that harked back to the muscular lines of the DB4 GT Zagato.

Under the skin, the ageing Jaguar XJS-derived platform of the DB7 had been replaced by an all-new aluminium and carbon fibre chassis. The engine, meanwhile, was a development of the 5.9-litre V12 used in the DB7 Vantage.

Just 25 examples will be produced, each tailored to its owner’s unique specifications.

The result was sublime. But it wasn’t quite perfect. Although glorious to behold, and brutally fast by the standards of its day, the V12 Vanquish felt big and heavy in comparison to rivals like the Ferrari 575M Maranello.

It was also saddled with a rather idiosyncratic single-clutch automated manual gearbox, while the interior was a veritable I-Spy of components pinched from sister companies Ford and Jaguar.

The aim of the Vanquish 25 is to take this iconic recipe and update it. Just 25 examples will be produced, each tailored to its owner’s unique specifications. Prices start at £350,000 for those with an existing Vanquish to use as a donor car, but R-Reforged can source suitable vehicles for a full turn-key service.

The attention to detail has to be seen to be believed. The technical team at R-Reforged is headed up by former Aston Martin vehicle engineering manager Adam Donfrancesco, whose past work includes the Vantage GT8 and GT12.

Each car is completely stripped and rebuilt at the company’s Warwickshire factory with some 350 changes to the styling, the materials and the engineering.

Aesthetically, the first thing that hits you is the car’s stance. It sits lower than the original V12 Vanquish with bigger wheels and a wider track, giving it a more assertive presence.

The front and rear bumpers are new items fashioned from carbon fibre, as are the wing mirrors. But perhaps the craziest example of Callum’s obsessive attention to detail is the design of the rear light clusters.

Rather than make do with the originals, he decided to build his own – an exercise that cost more than £450,000 once they’d been homologated to meet all the various international safety regulations.

A similarly fastidious approach can be seen in the interior. You’re greeted by the smell of rich leather from the moment you open the door. The hide comes from Bridge of Weir and it features Callum’s unique ‘deconstructed tartan’ pattern.

Rather than make do with the originals, he decided to build his own – an exercise that cost more than £450,000

Behind you, the largely pointless 2+2 seating configuration of the original car has been ditched in favour of a far more useful parcel shelf and a set of matching luggage from Mulberry. There’s also a sizeable boot and plenty of space in the cabin, making the Vanquish 25 a very useable grand tourer.

Just about everything that you see or touch has been painstakingly re-engineered, from the reshaped and re-upholstered seats to the bespoke 3D dials produced by British watchmaker Bremont.

The same tie-up has led to the creation of a unique pocket watch design that doubles as the Vanquish 25’s interior clock. It sits in a new carbon fibre centre console that also houses a neatly-integrated touchscreen infotainment system, complete with Apple CarPlay and Android Auto.

Some of the most significant changes are to be found under the skin. The big V12 now breathes through a bespoke carbon fibre intake system.

It also gets new cams, revised cylinder heads and a new exhaust system fashioned from F1-style Inconel. In total, this adds around 60bhp and 60lbft of torque, but equally significant are the improvements in linearity and the throttle response.

It also sounds magnificent, with a rich multi-layered growl that rises to a proper V12 crescendo when you work it harder.

And there’s a particular incentive to do so in this example, because it’s fitted with a six-speed manual gearbox conversion from Aston Martin Works.

The shift itself is heavy and a touch notchy, but it brings a level of interaction with that glorious V12 that simply isn’t available in any of this car’s modern equivalents.

A conventional torque converter automatic can also be fitted, as can the original ASM paddleshift system, but it’s the manual that best suits the analogue feel of the Vanquish.

The list of upgrades continues with the suspension, which gets new springs, dampers, bushes and anti-roll bars, along with stiffer uprights taken from Aston Martin’s GT3 racecar.

R-Reforged spent a full month honing the setup at Michelin’s Ladoux test track, alongside more than 20,000 miles of on-road testing. Much of that took place on the twisting A and B-roads around the company’s Warwickshire HQ.

Here, the Vanquish is a revelation. It’s not a small car, and neither is it an especially light one at circa 1.8 tonnes, but you can fling it around like an overgrown Caterham, revelling in the strong turn-in and the benign yet adjustable balance. Even on the damp winter roads of our test route, it feels utterly on your side. And despite an impressive resistance to body roll, the suspension provides a remarkable degree of composure, soaking up the worst of the bumpy and broken tarmac.

Another major area of improvement is the braking system, which now uses giant carbon ceramic discs from the current Aston Martin DBS Superleggera. These provide decent feel and plentiful stopping power, addressing one of the principal criticisms of the original car. But the most impressive thing about the Vanquish 25’s numerous upgrades is the way that they all gel together as a single package. As befits the calibre of the people behind this project, there are no clues to it being an aftermarket conversion. Every single aspect feels like it was designed this way from the outset.

Two decades down the line, the Vanquish 25 is not as rabidly quick as a modern supercar. And yet it’s a level of performance that’s far better suited to modern roads, allowing you to push harder, hold the revs longer and make more of that glorious V12. Throw in the rarity value and the almost limitless range of personalisation options and you might just have the ultimate analogue GT.

Get behind the wheel.