The car is everything that a fine Jaguar is - beautiful to steer, controlled but flat-riding, neutral at all sensible speeds on the road, equipped with very powerful brakes, and it positions its driver perfectly so the car pivots around him.
The usual chassis stability and traction gadgets are aboard and power is transmitted to the rear wheels via a paddle-actuated six-speed ZF auto box.
The Speedback GT also a shade softer riding than the XKR and generates marginally less road noise, perhaps because it rolls on slightly higher profile tyres, one of Brown's three-line demands.
Bottom line: no car maker this small could hope to build a chassis and powertrain of such all-round distinction. To spend millions trying would scupper a promising enterprise and a desirable car.
Brown has ‘previous’ with the 503bhp, 5.0-litre supercharged V8 as an owner and rightly believes it's perfect for his car, woofing gently and smoothly at low revs most of the time, but eating up any straight with a delicious bark if the driver gives the accelerator a half-interested prod.
Its muscular nature is clarified in the GT's claimed performance figures, with a 0-62mph time of around 4.6sec and a top speed that's limited to 155mph.
People seem to love the Speedback, if you discount a few snide web forumers. It certainly created a stir wherever we went in Yorkshire.
Most people instantly get the classic-meets-modern idea; the two aspects more likely to bother actual buyers will surely be the lack of old-time provenance for the car (DB believes this can be acquired) and the eye-watering price, which simply reflects the cost of hand-making something so superbly resolved and detailed.
But buyers who understand that are already circling - to the extent that Brown is looking for other coachbuilding opportunities. He's coy about saying where they lie, but they definitely exist. "Let's see the Speedback reach its potential," he says, "and then we'll see.
"We have half a dozen customers ready to go," says Brown, "and the car's ready too, give or take a few mods. We have staff of eight in Coventry – our job is to manage the skills of trusted suppliers – and a manufacturing system we know will work. In March 2014, this car was no more than some sketches on paper."
At the time of our drive, there was only one completed Speedback GT in existence, our test prototype beautifully built by Envisage of Coventry. Envisage is one of those accomplished but rarely noticed prototype builders that have always discreetly fed the big companies with their news-making cars.
Envisage will build the production Speedbacks, too. Brown has already said he'll never make more than 100 Speedbacks but given that the XKR is heading for the exit, the tally might be fewer than that because finding donor cars may get difficult.
Brown currently owns about 10 - convertibles are best because of the extra 'beef' in their lower bodies - but says he knows how to find another 50. "We have some big decisions to make about the scale of our business," says Brown. "We'll do it when the car feels like it's properly launched."
Those decisions appear to have been made, with David Brown Automotive opening its first dealership in Germany in 2016 and followed that up with its first appearance at the Geneva Motor Show in 2017.