Good: surprisingly understated luxury (in this spec), comfort, refinement, handling, quality

Not so good: big, expensive, thirsty, ageing design, lack of new electronics and infotainment

At first, the Bentley Flying Spur doesn't seem all that special. Certainly, parked outside on a grey Belfast day, its coachwork finished in a subtle sheen of metallic sea grey, it didn't scream HERE IS AN EXPENSIVE BENTLEY!!!

Perhaps that's the point though. Slide in behind the wheel (which takes a team of craftsmen 16 hours to assemble and hand-finish) and you're presented with a pretty familiar dashboard. The interior design of neither the Spur nor its close cousin, the Continental GT (both of which are direct descendants of the Volkswagen Phaeton, it's worth noting) hasn't changed much since 2003 - the same upward-sweeping wing motif, the same spot-the-Skoda-bits central touchscreen, the same handsome instruments and the same wall-to-wall quilted leather and woodwork.

Of course, you can have any level of garish, eye-melting colour you want on the inside of your Flying Spur. Bring along a sufficiently stuffed cheque book and they'll match the dye of the leather to the inside of your lover's eyelids if you fancy, but here in our test car, it was all gentle-on-the-retinas piano black wood and exterior-matching sea-grey leather. Subtle in the extreme, to the point where, again, it would be easy to forget how expensive the thing is. 

In fact, once you start to poke around the now-antiquated touchscreen and infotainment system, you start to realise how far Bentley has fallen behind the curve. It all works well, and you can't fault the quality, but the fact is that these days a relatively humble Mercedes-Benz E-Class or BMW 5 Series has a cabin with more tech and equal levels of assembly. 

Still, there is charm here in abundance. The seats are remarkably comfortable, for a start. All that quilted cow has gone to good use if it can keep you this cosseted for this long. The little things start to work their magic too. The chromed organ-stop switches for the air vents for a start - they feel tactile and slightly magical compared to the bland plastic wheels most car makers use to open and close their vents. Other little things, such as the fine stitching and the slimness of the steering wheel rim, all contrive to make the Spur start to feel that little bit more special.

And then you get in the back. The legroom is generous enough, and the adjustable, heated seats are lovely. The fridge mounted in the arm-rest is pretty nice too (and perfectly shaped and sized to hold two champagne bottles, which somehow is not at all surprising), while the Naim stereo system is good enough to make your ears regret leaving the house. But the nicest bit is the fold-down picnic tables, finished in the same piano black veneer as the dashboard. Any car that gives you such an expensively-engineered place to rest your sandwich is a great car in my book.

Back up the front, and behind that imposing grille, lies the same 507hp twin-turbo 4.0-litre V8 engine as we sampled last year in the Continental GT V8S. Here in the Flying Spur, it has been to finishing school and had both its bombastic edges knocked off and its volume reduced. Whereas in the GT V8, this engine sounds like someone pouring vats of nails and scrap iron into the middle of an ACDC concert (and yes, it's as wonderful as that sounds), here in the Spur, it's more like someone tinkling out a Debussy tune on a finely balanced Steinway. In the next room. Refinement is utterly fabulous, and while there is a sharp-edged V8 growl when you rev it, the rest of the time it's utterly discreet and reticent in its noises.

Not in its performance, however. This engine doesn't have the sledgehammer hit of the big 6.0-litre W12 unit, but it has serious grunt nonetheless. Any engine that can accelerate a 2.4-tonne car from standstill to 100km/h in little over five seconds is worthy of the deepest respect. Just as you don't expect an aircraft carrier to be fast (yet they are capable of out-running their escorting ships), so the Bentley can humble many a supposed performance car, but can do so without apparent effort.

In dynamic terms, it's soft - and that is just as it should be. There is a relaxed progression about the way the air suspension goes about its business, and only really sharp urban bumps upset its composure, at which point there is a whump and a noticeable shudder through the structure, which serves to remind you that this car's underpinnings date back almost one-and-one-half decades.

And then you find a twisty road. Take a moment to select the sportiest settings for the dampers (don't worry - the effect on the ride quality is negligible) and pull the hefty gear selector for the near-seamless eight-speed automatic transmission into S. Now, deep breath, point and squirt...

What you find is an unexpected level of precision and dynamism below a thick layer of velvety comfort, rather as if someone had stashed a Rolex watch beneath a comfortably upholstered pillow. The Spur rolls a bit, and you are never other than unaware of its size, mass and bulk, but it can be thrown through a set of challenging corners with no little verve and no little enjoyment. Part of that enjoyment, true, comes from driving such a car in a manner quite unbecoming, but another part is that it's just bloody good fun. 

So, the Spur, which initially had seemed so underwhelming given its lofty reputation and loftier still price tag, turns out to be something rather special indeed. A car with a surprisingly engaging naughty streak. Flawed? Certainly. That cabin needs a major update and the infotainment system is shown up by cars costing a tiny fraction of the price, but this is still a very charming, very wonderful car.