To describe a machine as 'unique' is an understandably rare occurrence, but, in the case of the Challenger, entirely correct. Built by a retired engineer, an experienced and expert builder of three-wheelers, this is his ultimate machine, combining engineering excellence with a staggering originality of concept, having been featured in articles in both newspaper and magazines.

The motive power is a three-cylinder 'radial', using BMW R.100 cylinders and pistons as the only stock items, the rest being purpose-designed and built to suit this vehicle. The crankcase, crankshaft and rods are unique to the engine and engineered for long life, the 'cases being machined from solid bar in the maker's comprehensively-equipped workshop.

The gearbox is Citroen GS, 5-speed, with inboard discs and the hi-tech front suspension is twin-wishbone, incorporating front-wheel drive. The rising-rate rear suspension attaches to the monocoque, fabricated from epoxy-bonded aircraft-alloy 'honeycomb' composite. Seating two with ease, the cockpit is leather-upholstered.

Performance is quite mighty, the engine being very loud and muscular, the acceleration formidable and the light weight and 'planted' road-holding making this a machine besides which most other three-wheelers are, in the maker's opinion, under-powered.

Most definitely not for the faint-hearted, the Challenger has proved fast and reliable, both in the UK and abroad, and this iconoclastic machine is only being sold by its maker because a knee operation has prevented its use. Now 'on the button' again, complete with V5, papers and articles, with further advice and a range of spares available from the vendor, by arrangement.