It was the German long-nosed streamliner, with flushed, raked-back screen, narrow dewdrop turret and raised doors - the fastest and by popular consent the most beautiful E-type the factory built - that crashed fatally on a streaming wet track at Montlhery in '64 killing several trackside officials as well as Peter Lindner. Many years after this horrific accident, Lynx was commissioned to reconstruct the wrecked car, salvaging what it could from the remains.  Subsequently, it has built other Lightweight facsimiles, the latest to a special brief from Mr X who wanted to capture the flavour of the Lindner/Protheroe cars without exactly replicating either. He was to take delivery the day after we went to drive it at Lynx's East Sussex base. Incidentally, the Ecurie Ecosse-blue is not a clue to the owner's identity: when you're forking out £150,000 for a bespoke car, you get to choose the colour. The buyer fancied Scottish livery.

Although it has been built and set up for road use - Goodyear Eagle NCT tyres (on the original back wheels made for Lindner's car), fairly supple suspension, neatly-trimmed and sound-insulated interior, cooling trunks to the footwells, proper demisting, civilised exhaust noise and so on - Mr X's reconstituted E-type is powered by what is close to the ultimate in XK engines. It also looks like a racer with its proud body rivets - "a nice feature," says Lynx's Chris Keith-Lucas talking us through the car - and flip-up filler for the Le Mans 45-gallon fuel tank that occupies most of the boot, its lid swinging up on a protruding top hinge that is as original as it is unsightly.

Lindner's car had an aluminium central monocoque; Mr X's (like CUT 7) retains the inner steel shell of its E-type donor, though all the outer skin bar the bulkhead ahead of the screen is in aluminium, handcrafted in Lynx's workshops. "The shape and size of the rear window is also more CUT 7 than Lindner. When Chris lifts the bonnet, he gets carried away. "The engine is spot-on as it should be," he enthuses. "It's a full-house, injected, wide-angled, dry-sumped 3.8 with virtually nothing in common with a standard E-type. This power unit is what the car is really all about..." It does look and sound magnificent.

The block is an iron casting like CUT 7's (the lighter aluminium blocks were notoriously troublesome) and the crankshaft - longer than an ordinary E-type's so it can drive the dry sump's two scavenge pumps - is turned from a solid steel billet. The camshafts are authentic 'Lightweight' copies, the pistons from Cosworth, and the cylinder head - its rare wide-angle configuration making space for stomping great valves - prepared by former Weslake specialist Jack Cramp (who did the original D-type heads). Lynx's ace engine builder, Tim Card, describes the American Carillo con-rods as "works of art" - pity you can't see them. At least the Lucas mechanical fuel injection, most of it original (though the air trumpets were specially made), is very visible. As the injector pump renders the engine's distributor inaccessible, Lynx has for convenience fitted electronic ignition: the only concession to modernity.

"The factory never got more power from an XK engine than one like this," says Chris Keith-Lucas. He estimates the output at around 340bhp at 6,000rpm, which is the engine's safe limit even though it feels as though it will rev to 8,000. "The great challenge," says Chris, "was to tune the engine so it was fit for road use." Lynx has done a terrific job; the only other E-type I've driven with Lucas fuel injection was a temperamental beast which snorted and spat and hiccupped at anything much below 4,000rpm. Mr X has an engine that's as potent as it is deliciously tractable, largely due to the persistence of Tim Card who "ignored everything anyone had ever told us about the injection system" and developed a set of calibrations that work a treat with a lowered compression ratio suitable for four-star fuel. "We've got this engine working really well now." Although Jaguar's fast and beautiful Lightweights were generally eclipsed at International racing level by the red devils of Maranello, for production-based cars they were staggeringly quick.

Mr X has in Lynx's reincarnation a car that's eminently suited to its intended role - a racer tamed for fast road use that, unlike so many modern supercars, is not intimidatingly wide; it's a mouth-watering combination. Because the roof is lower, getting in over the wide sills is even more tricky than in an ordinary E-type; pulling out the steering wheel - a big wood-rimmed, alloy-spoked original - helps create space when clambering into the driver's seat of this LHD car, its blue-trimmed buckets tailor-made by Lynx for the new owner. Ahead, a familiar black E- type dash with its lovely big Smiths dials and well-ordered switchgear; nothing pretentious or unnecessary, nothing surplus to requirements, though I'm conscious of the threatening ridge in the low, cloth-lined roof just above my forehead. There's little spare room in this lightweight streamliner, its quilted tunnel and shallow windows promoting a feeling of cosiness if not claustrophobia. There's not much in the way of ventilation, either. Even with the sliding windows open, the cockpit is something of a sweatshop in sunny weather.

Switch on and the fuel pump in the vented tail whirrs noisily. Prod the starter button and the engine bursts into life with a deep-chested bellow. The quality of the noise will raise goose pimples at a hundred paces but it's sufficiently muted to avert offence. The clutch is heavy with its bite in the first half-inch of travel. Lynx's new owner, John Mayston-Taylor, makes my first few shifts clumsy by comparison with his. You soon adjust, though, to the heavy, razor-sharp throttle - no XK engine I've driven before 'blips' so responsively as this one - and the long-throw travel of a four-slot gearlever that engages cleanly without graunching synchromesh. Mr X eschewed the hefty five-speed ZF box of the Lindner car, which negated some of the poundage saved in other departments. It also sapped more power.

Considering its competition credentials, the Lynx engine pulls remarkably cleanly from little more than idling speeds. Clog the throttle at low revs, and you drown the delivery. Feed it in progressively and the big-six growls sweetly and hauls hard, power burgeoning as the revs rise. Beyond 4,000rpm, it's into rocket mode. Although the competition Lightweights were homologated at under one ton, Lynx's facsimile is presumed heavier. Assuming a weight of 24cwt, the freshly-minted clone has a power/weight ratio of around 285bhp/ton, which translates into a 0-100mph time that must break 15 seconds - well inside the yardstick for a seriously fast car. Top speed, as geared, is probably around 150mph, but a longer final drive would give a higher maximum: Protheroe's streamliner did 168mph at Rheims.

Neither traction nor grip are cause for concern. What's more, the car's stance (so important if a car is to look right) does not offend the eye on those NCT Eagles - 205/70 fronts, 235/70 rears. For track work, the suspension set-up would probably feel too soft; on the road, it's just about right, on the supple side of harsh. There were no worries about the enlarged brakes, either, even though solid discs (not ventilated ones) are retained at the front. Chris Keith-Lucas defends the use of a Kelsey Hayes servo: "The 'Lightweights' didn't have one, but the brakes are awful without it."