Given that the viewing public have been successfully hoodwinked by a number of faux documentaries over the years – from Peter Jackson and Costa Botes' wonderful Forgotten Silver to the horror phenomenon that was The Blair Witch Project – its a little surprising that they could be so fooled once again. But then again, maybe not. Those of us arriving at the film over a year after its first Australian release are doing so with its mockumentary status an integral part of the sell, but were it not for that then I'd argue that the clues are a lot, lot harder to spot than they were in Forgotten Silver, whose level of straight-faced preposterousness was at times jaw-dropping. Kenny plays it unwaveringly straight, with nothing here that pushes credibility too far – even his sometimes hilarious monologues are believable as the product of a natural working-class humour.

Exposing the gag does the film no harm at all and if anything increases our appreciation of the lengths to which the filmmakers – specifically director Clayton Jacobson and his brother and co-writer Shane, who plays Kenny – have gone to in order to convince us of the authenticity of their lead character, working directly with Glenn Preusker, the manager of real-life toilet installation company Splashdown to get every aspect of Kenny's working life down pat. Preuska's involvement went beyond that of technical advisor – he also supplied all of the drainage equipment, several of his staff appear in the film (he's also in it himself, as is director Clayton Jacobson as Kenny's snooty white-collar brother), and he even put up the $600,000 to $800,000 (estimates vary) production budget.

It's this working relationship that has provided the filmmakers with the most convincing evidence that Kenny is the real deal, as he and his team carry out the installation and maintenance of toilet facilities at a number of real-world events, including an air show, a rock festival, and the high profile Melbourne Cup. This is taken a sizeable step further with Kenny's trip to the Pumper and Cleaner Expo in Nashville, Tennessee, which he is asked to attend in place of his indisposed boss and which dominates the second half of the film. As Kenny tours the show, starry-eyed with wonder at the exhibits and cheerfully interacting with salesmen, the drama and documentary elements become so perfectly entwined that it becomes impossible to separate the two.

But the real draw here is Kenny himself, an on-screen celebration of the wit and resilience of Australian working man and a character Shane Jacobson wears like a second skin. In common with many a true-life counterpart, Kenny has an opinion and philosophy on all aspects of his life and work, most of which are funny in a way that always sounds spontaneous and unscripted. We get to hear of the problems of blocked toilets ("another classic example of someone having a two-inch arsehole and us having only installed one inch piping), the perception others have of his trade ("they think I'm the poo monster"), and on why men can spend extended periods on the toilet reading the newspaper (they apparently get over the shock of the smell much faster than women). He provides a very plausible sounding explanation of the origins of the word 'shit', but reserves his most negative comment for his experience-formed views on marriage: "Cut out the middle man," he suggests, "find someone you hate and buy them a house."

Part of the joy comes from Kenny's way with words and a use of English that is uniquely Australian, the cruder terms of the trade frequently giving way the almost charmingly amusing words like "bum" and "poo," which take on a sort of innocence when Kenny describes the Nashville Exhibition as "Poo HQ" or suggests that walking into a toilet just after someone has made extended use of it is like "being hit in the head with a poo bat." It's Kenny's cheerfully naturalistic delivery that makes lines that are amusing on paper sound hilarious when spoken – one in particular made me laugh so hard I had to pause the DVD for five minutes to stop giggling and get my breath back.

The upshot is a complete engagement with Kenny as a character that renders irrelevant the fact that his image and natural charm is, to a degree at least, manufactured. It's easy to sympathise as he juggles his grouchy father (played by his real father, Ronald Jacobson) and unwaveringly hostile ex-wife to maintain a meaningful relationship with his young son, and to share his concern when the boy goes missing in the crowds at the Melbourne Cup. His blossoming friendship with air stewardess Jackie is particularly touching, not least for Kenny's almost childlike innocence of Jackie's seemingly obvious affection for him.

That Kenny was such a hit in Australia seems in retrospect less surprising than it apparently was to its makers. Warm-hearted without slipping into sentimentality, it's understated in its handling of a subject that seems tailor-made for a cruder approach, and is as witty in its execution as Kenny's sometimes priceless words of wisdom. While in many ways typically Australian, Kenny has all the ingredients to connect with a receptive international audience, and in a time when idiot comedy shows no sign of abating, it's a refreshing reminder of the sophistication and humanity on which so much of the best comedy is built.

The 1.78:1 anamorphic transfer has an authentic documentary feel without downgrading the picture to artificially create a rough vérité look. The result is very pleasing, with detail, contrast and colour all about right, no less than you'd expect from a modern digital transfer.

There's an argument for suggesting that one of the mockumentary giveaways is the quality of the sound mix. Now there's no reason at all why a documentary should not have a great sound track – check out Kevin Macdonald's Touching the Void – but while the camerawork here is authentically grabbed-on-the-fly, the soundtrack occasionally has the punch and dynamism of a Hollywood actioner, notably at the air show that Splashdown are servicing, where planes soar around the room with a clarity and bass that could shatter glasses. Both 5.1 and DTS options are available, with the DTS the clear winner on all fronts.

Audio commentary by Clayton Jacobson and Kenny
Before I proceed on this one, note the names above. We're not talking the director and his lead actor here, but the director and his lead character. Yep, if you're looking for some insight into how scenes were so ingeniously faked, as I was, then you're out of luck. The commentary here is clearly intended to be part of the mockumentary deception and involves the two men remarking on scenes and characters as if they were for real, with Kenny throwing in stories that these observations inspire. It's convincingly performed and rather fun in its own right, but the joke only goes so far.

Lifting the Lid (22:11)
A featurette made for Sky Movies to promote the film, with Kenny met at the airport and taken on a whistle-stop tour of UK locations, including a UK portaloo company and the Reading Festival (which Kenny assumed was all about books), at which he exchanges greetings with a number of his fellow countrymen and women to whom he is already a figure of fame. This plays almost as a bolt-on to the film itself and is rather fun.

Bonus Scenes (15:19)
A collection of cut and extended scenes. They're all enjoyable, but of particular interest are a hospital scene in which Kenny's father embarks on an unbroken monologue of complaint and extended footage of Kenny's air trip to Nashville, which builds on his interaction with Jackie.

The UK Trailer (1:30) and Original Trailer (1:44) are a reasonable sell, but both include that line I made a point of not quoting, so don't watch either before the movie.

The advance word has been terrific on Kenny and it's all justified. Avoiding the obvious scatological humour, it creates a witty and endearing working class hero from the most unlikely of professions. Rumours are flying of a Kenny TV series, so enjoy the original now before it becomes victim of exposure overkill. Contender's DVD looks good and sounds great and includes all the right mockumentary extras. It's just a shame it doesn't include a genuine commentary from the Jacobson brothers and some insight into how the fakery was achieved – for that you'll have to go to the Australian 2-disc Collector's Edition.