The John Cooper Works badge means a lot to Mini’s substantial fan base, but which might not ring bells with the uninitiated. The idea behind it is straightforward: take an ordinary Mini model (Hatch, Clubman, Countryman) and add more power and a smattering of other tweaks. This time, they’ve done it to the Convertible.

The Mini Convertible is already a fun car, with the combination of top-down motoring and Mini’s fundamentally cheerful predisposition making it quite an entertaining runabout. So you can imagine what happens when Mini upgrades the engine to a 228bhp 2.0-litre turbo and tinkers with the exhaust to create the kind of burbles and pops you’d expect from a much older roadster.

That happy little pop-pop-pop is one of the most alluring features of this model, but the exhaust note means that the JCW demands even more attention than the Cooper S Convertible. Driving it forces one to adopt a blithe indifference to raised eyebrows — depending on where your merry journey takes you, burbling into town in an open-top Mini making that kind of racket is likely to turn a few heads.

The front of the JCW has undergone a subtle facelift, with fog lamps replaced with vents to improve airflow. You can also get Union Jack patterns pretty much everywhere, including on top of the fabric roof. Again, this is not an understated car.

The hatchback segment is littered with excellent cars. If your priority is practicality, nearly everything else in this part of the market will outperform the JCW Convertible in most measurable ways — boot space and rear passenger space in particular. But by taking the roof off, Mini has created a compromise. What you lose in daily usability, you make up for in driving fun.

The roof folds in a reasonable 18 seconds and can be done while rolling. This means that it’s genuinely useful as a soft-top in Britain’s changeable weather. But it also cuts boot space from 215 litres with the roof up to 150 litres with the roof down — just about big enough for two people’s luggage, but not much more.

Which is lucky, as there’s not much room for rear passengers either. Those back seats are more useful as an interior storage shelf, as the compartments in the car are rather meanly proportioned and there’s no way you’ll fit adult companions behind a normal-sized driver and passenger.

Fire up the JCW using a rather silly switch in the middle of the car and you’ll immediately notice the difference between this and the regular Convertible. If the roof is down at this point then even better, because you and everyone around you will be treated to one of the best exhaust notes in this class.

Mini’s ‘go-kart’ handling is among the best in the segment, too. It’s fine for easing through city traffic, but comes into its own on spirited B-road blasts through the countryside. The roof-down effect means that the JCW is like a refined, subdued version of a classic roadster — a compromise between driving fun and mod-cons.

You’ll hit 100kph in 6.6 seconds, a figure that places the JCW Convertible in hot hatch territory. But this little rocket prefers twisty roads rather than the motorway. In fact, wind and road noise becomes intrusive above about 100kph. This car’s top speed of 240kph is faintly ridiculous, but means you can give the big boys on a derestricted highway a run for their money.

Mini is a premium brand and all of their models cost considerably more to buy than broadly equivalent rivals. But it’s impossible to compare the Mini Convertible JCW to anything because, well, there’s nothing out there like it. If you want a characterful convertible hot-hatch then you probably want one of these. Anyone who wants a speedy, open-top car and doesn’t need to take passengers on a regular basis should take a look at this car. If you’re prepared to swap the dull practicality of a budget hatchback for exciting impracticality, then the Convertible JCW is your best bet.