Thornley Kelham has taken the covers off the latest addition to its ‘European Collection’ of re-imaginings at Salon Privé. Set to complement the existing Coupé, just 25 examples of the Jaguar XK Roadster will be built, each one taking more than 6,000 hours to complete.

The XK120 established Jaguar’s reputation after the war, briefly holding the title of the world’s fastest production car. While the Roadster will not trouble today’s supercars, it develops up to 200bhp more than the 1940s original and is lighter by some 190kg, achieved through the integration of modern engineering beneath the XK’s celebrated silhouette. The vision has been to create “something that could have emerged from Browns Lane in the late 1950s as a ‘skunkworks’ project”.

A major contributor to that weight loss is a hand-built, all-alloy version of the XK’s 3.8-litre straight-six, replacing the original iron block. Incorporating modern fuel injection, electronic ignition and drive-by-wire throttle, it is intended to improve refinement and reliability without losing the engine’s character.

Two specifications are offered: a GT-orientated tune producing 300bhp, or a fast-road setup that revs to 7,000rpm and delivers 360bhp and 318lb-ft of torque along the way. Exhaust options include a stainless-steel system or a full Inconel alternative.

The transmission has received similar attention with a new five-speed gearbox replacing the donor car’s four-speed item. As the original only used a synchromesh on third and fourth, it should bring a marked improvement in driveability. The open differential also makes way for a mechanical LSD.

Further dynamic upgrades include a completely new suspension arrangement. Bespoke aluminium double wishbones replace the original torsion bar setup at the front, while the leaf springs and live axle at the rear make way for trailing arms with Intrax coilovers and Eibach springs.

Braking is by 295mm drilled and ventilated discs front and rear, clamped by four-piston callipers, while the steering now uses a Quaife rack-and-pinion in place of the XK’s recirculating ball system. The ratio is tightened to 14.4:1 with just 2.5 turns lock-to-lock, with switchable electric assistance available as an option – as is adaptive damping.

More than a third of the 6,000-hour build is devoted to the revised bodywork, formed in aluminium and assembled by hand. Each body is seam-welded for stiffness and finished with smoothed external joints, before a further 1,100 hours are spent on paintwork.

The styling is the work of Paul Howse, formerly of McLaren. His revisions are subtle but deliberate: the roofline is lowered by 63mm, the stance is more assertive, and the proportions adjusted to emphasise the XK’s curves without losing its identity. The wheels have also been updated, featuring a hand-made centre-lock design with stainless spokes, unique hubs and triple-eared spinners.

Inside, the theme continues with Wilton wool carpeting and Connolly leather, Alcantara and woven fabrics offered for the seats. While the dashboard mirrors the layout of the original, it’s entirely new, with finishes ranging from chrome or bright nickel to darkened or anodised. Air conditioning, Bluetooth and Apple CarPlay are integrated, while heated seats can also be specified.

Simon Thornley, director of Thornley Kelham said their interpretation is “Respectful of the original but bolder, more focused, and ready for the open road in every sense.”

All this work inevitably comes at a price, with the Roadster starting from £750,000 before factoring in the cost of a donor car.