It’s ten years since Theon Design set up its workshop to rejuvenate and transform the classic air-cooled Porsche 911. Over the past decade, the Oxfordshire-based outfit has built a series of bespoke customer cars, taking the iconic 964 series 911 as the base for each uniquely personalised car.

Founded by designer Adam Hawley and Lucinda Argy, the business brought together a host of experience across luxury automotive design, with each and every build based on a precise customer specification. Models like the GBR002, which started life as a 1992 964 C2, and the forthcoming Theon R, an ultra-light high-power variant, showcase a wide variety of skills, from custom machining and parts making through to interior finishes and trims that far exceed the quality of the original cars.

To mark the anniversary, Theon has launched its first online configurator, a dangerously diverting desktop offering that offers an insight into the scope of personalisation across the company’s three key offerings, Coupe, Targa and R. It’s easy to lose an hour in the system as you click and select your way through a rich variety of exterior and interior colours and options.

A fine showcase of the Theon approach has also been unveiled, the latest Theon Coupe. This 419bhp, 4.0-litre model is finished in Oak Green Neo Metallic with a custom Beechnut leather interior and champagne trim details. It takes around 18 months from commissioning to receive a car finished to this level of specification; although it starts with a 964 donor car, the Coupe features bodywork in F1-grade carbon fibre, keeping the weight down to just 1,150kg.

‘As with every commission Theon Design undertakes, this project began by listening to what the client wanted – not just how they wanted their car to look, but how they wanted it to feel. That informed every aspect of the development programme, from the engine, transmission, and brake package to spring rates, damper calibration, and steering response,’ says Hawley.

Coupled with the completely rebuilt and remapped 4.0-litre air-cooled flat-six engine, Theon points out that the Coupe ‘has a better power to weight ratio than a 992 GT3 RS’. Destined to live in the UK, the car has semi-active suspension and a 5-speed manual gearbox. Brakes and calipers have been upgraded with units from the Porsche 993 RS.

Importantly, like other noted small manufacturers who have made the 911 their canvas, Theon has no connections to Porsche AG. For Hawley, the model – particularly the 964, which was manufactured between 1989 and 1993 has ‘legendary integrity of design and engineering. The car’s proportions, mechanical character and unfiltered connection with the driver are fundamental to its enduring appeal,’ he continues, ‘Our ambition has always been to elevate those qualities while respecting the principles behind the original design.’

While the exterior panels and engineering fundamentals are given a colossal overhaul, the interior provides another facet of customisation and craft. The combination of Beechwood semi-aniline and nubuck leather trim is paired with Recaro CS seats, while the original cockpit and dashboard architecture is given subtle updates, from new aluminium window switches to a discrete new climate control system and all-new electricals to save more weight.

‘We don’t measure progress by the changes we introduce, but by how naturally each enhancement belongs to the car,’ Hawley says, ‘The result must feel cohesive, fully in keeping with Porsche’s engineering ethos and unmistakably true to the spirit of the original 911, as it subtly evolves into a distinctly personal character shaped by its owner.’

Theon Design commissions start at £435,000, more information at TheonDesign.com, @Theon.Design, Theon-Configurator.com