The inexorable rise of the Radical sportscar marque in seven years has undoubtedly been an entrepreneurial British success story. A triumph of marketing and innovation fuelled by giving punters exactly what they want.

I've been an ardent fan of Phil Abbott and Mick Hyde's mould-breaking products since I first clapped eyes on the prototype 1100 Clubsport, without body, at a Mallory Park 750 Motor Club meeting in 1997. A few weeks later, I watched Hyde give it a promising race debut at Brands Hatch.

Then I drove the 1100cc Kawasaki ZZR motorcycle-engined machine flat out at Snetterton. Such was its poise and cornering power, with ingenious transverse 'Nik-link' roll control, that I hardly noticed it was wet!

Within a season, it was aspirational stuff. Dozens of competitors started to bang on Radical's door in Peterborough. It's been the same with each new model. The Prosport, full-blown SR3 (a great-looking scaled-down World Sportscar) and now the SR4, brand-new 1200cc successor to the original.

But the dynamic duo are never satisfied. Always stretching the envelope of performance with their brilliant multi-tasking test driver/engineer, Michael Vergers, in the vanguard of development, they just want to go faster. Currently, their ultimate tool - kitted for road use, if you please - is the turbocharged SR3 which has lapped the Nürburgring's public Nordschleife in 7m19s. Vergers reckons 6m50s is on, given perfect conditions!

Having driven the set of regular Radicals for a forthcoming feature, I sampled 'the beast' first-hand on Brands Hatch's Indy circuit last week. For an adrenalin rush I know of no equal. I've certainly not been round there quicker.

Built by Radical's Powertec division, the stretched 1500cc Suzuki Hayabusa engine belts 260bhp to the wheels at half a bar of boost. Rampant acceleration necessitated a flurry of upchanges, reduced Cooper Straight to a blur, yet I felt relaxed despite my reactions being reprogrammed with each lap.

I pitted to savour the experience: the chassis's balance through Paddock, finely-honed handling, tenacious Dunlop slicks and the engine's lag-free whoosh matched by stop-on-a-sixpence brakes. I was quite prepared to clamber out when Vergers leaned into the cockpit. "Ready to be scared?" he grinned, flicking an anonymous switch on the dash. Suddenly another 40bhp at my right foot sharpened its claws.

Three hundred stampeding gee-gees and just 500kg makes for a pretty explosive cocktail. Sweeping under the start gantry, I sized up an 'ordinary' SR3. In an instant, I'd made up the 40metres, swept round it over the crest and was surging through the cambered apex in fifth gear. I was, however, totally unprepared for what followed. Having to snatch sixth up the hill towards Druids - in a car geared for 160mph and still accelerating wildly - blew my mind. Truly a defining moment in one of the drives of my life.

Radical SR4s up the pace

The performance of Radical Sportscars latest SR4 model out of the box suggests that lap times will drop in the Matador Tyres-backed Biduro series, which opens at Donington Park on March 27.

Ex-Superkart star Chris Stoney and teenager Alex Mortimer were among the pacesetters who lapped the 1200cc Kawasaki-powered cars in the 47-second bracket on Brands Hatch's Indy circuit last Tuesday.

At least 15 of the distinctively styled SR4-s are expected to be out for the first race. Production is running at three per week in Peterborough.

Among the competitors stepping up from the original 1100cc Clubsport models - which should continue to be competitive in the championship - are Terry Freeman, Adrian Mardlin and Duncan Williams, all of whom showed their speed last season.

Hotshoe Mick Mercer's SR4 will be his sixth from the marque and completes a set of four models to date. And Brian Casey, who had the seventh Clubsport, has an SR4.

Of additional interest this year will be the Czech-made Matador tyres, which have proved both quick and durable in testing.

Radical's Phil Abbott said: "There seemed to be no-drop-off after 100 laps of Estoril".