This car, Eagle’s new Lightweight GT, is not one of those ‘subtle transformations’. It’s an homage to the original Lightweight, but it’s a road car, a supercar GT that can be driven (fast) all day long in complete comfort. It joins three previous Eagle special editions: the Speedster, the Low Drag GT and the Spyder GT.

Based on a Series 1 E-type, it’s been stripped down and every panel replaced in modern grades of lightweight aluminium. The shape is an homage to the first Lightweight but the sills are deeper, giving more strength and allowing lower seating. Meanwhile, its steeper screen rakes boost aerodynamics, and the arches have been enlarged to accommodate 16in peg-drive magnesium-alloy rims.

It looks absolutely right, and once inside you’re immediately struck by the quality of the fittings and the sheer roominess – the latter due to clever changes to the floorpans, pedal mounts and rear bulkhead. It’s unmistakably E-type, with the toggle switches, alloy centre panel and black dash, but it’s enhanced by Eagle’s specially developed seats, curved console swoop and gorgeous quilted headlining. Despite that long bonnet an E-type isn’t a big car, yet the Lightweight GT isn’t at all cramped.

Every Eagle E-type is built to customer specifications, and this first Lightweight GT has had all the boxes ticked, starting with the firm’s 380bhp 4.7-litre all-alloy version of the XK six-cylinder. Although fuel injection is available, this is such a well developed engine that it runs beautifully on triple SU carburettors (I know – I’ve tried them on an Eagle Speedster), or on triple sidedraught Webers should the customer require the wide-angle, big-valve cylinder head – which this one absolutely did.

They also specced the rortiest exhaust option. You certainly know about it when the Lightweight GT fires up, although it never sounds uncomfortably loud. The engine is incredibly tractable from low down, but there’s a distinct powerband from around 3500rpm when the car just takes off. It all sounds deliciously raw.

The newcomer gets away with the peaky engine because the total weight is just 1017kg (2242lb), which is 300kg (660lb) lighter than a stock S1 coupé. Why not sub-1000kg? Because that would mean doing without the neat Eagle air-con unit or the soundproofing. And actually that weight reduction is phenomenal. It’s thanks to the alloy body, of course, but also the magnesium-alloy used for the case of Eagle’s five-speed gearbox, plus the bellhousing, diff case, sump and rear hub carriers.

The exhaust manifold is Inconel and the system titanium, and the set-up is uncannily light as well as sounding out of this world. There are countless more weight-reduction examples, right down to specially made alloy wheel spinners.

You can really feel the difference, not just in the performance but in the handling and steering response, too. Jaguar developed the E-type to work with crossply tyres, and remarkably it never changed the geometry of road cars for the radials that followed. Eagle’s years of development have perfected the ride and handling, favouring bespoke adjustable Öhlins dampers; the car’s reduced weight means they can be left relatively supple while still giving sharp, precise handling. The steering is light and the E-type reacts to inputs like a much smaller sports car.

More than 8000 hours go into the build of a Lightweight GT, and the materials used are the best of the best. This means you’re looking at well over half a million to buy one – but it’s the best E-type we’ve ever known.