If you're new to 70s/80s Hong Kong martial arts comedies, the early scenes in Sammo Hung's 1979 Knockabout [Za jia xiao zi] – with its bad jokes, silly slapstick and wildly exaggerated pantomime acting – will probably leave you wondering just what the hell was going through Bey Logan's mind when, on the commentary track, he describes it as a genre classic. But, comedic mugging aside, this is par for the course in this particular sub-genre, setting your lead characters up as buffoons who make out they're tougher than they are (it's still happening – check out Stephen Chow's recent Kung-Fu Hustle), only to have them later learn the skills that will enable them to show their worth. Thus the comedy comes first and the real action comes later. And believe me, it does come.

The story centres around two hapless confidence tricksters Yipao and Taipao, who after failing to con and later mug an old man known as Silver Fox, beg him to take them on as students after he proves a far better fighter than either of them. He reluctantly accepts and trains the two, but unbeknown to them he is not quite who he seems.

There's actually quite a bit more plot than this brief summary suggests, including a couple of surprise twists, but the meat of the film lies initially in its comedy – which is as broad as the Yangtze and very much a matter of taste – and its action, which starts small and steadily builds as Yipao and Taipao develop their skills. Early fights are played at least in part for laughs, with Taipao repeatedly kicked over the same table in a set-piece that looks straight out of acrobatic clown school, and Yipao tapping a goon on the shoulder with his raised leg, mesmerising him with his foot, and then kicking him over. If never really laugh-out-loud, these moments are still a good deal of fun and generally play better than the straight-up silliness, though the sequence in which Yipao and Taipao hungrily devour a large meal in a series of rapid-fire cuts put a wide smile on my face. Music cues are borrowed from Ennio Morricone (The Good, The Bad and The Ugly) and Alex North (Cross of Iron); two gay kung-fu assassins beat the pair up and walk off hand-in-hand (I know, but this is Hong Kong in 1979); people get hit and immediately break out in saucer-sized bruises; and in one particularly outlandish case, the victim accumulates a series of tennis-ball sized lumps on his head.

Given that the film was promoted as a showcase for the skills of first-time star Yuen Biao*, you just know that something special is on the way, but we're over half-an-hour in before we get a real flavour of what we're in for, as Yipao and Taipao spar following a training session with Silver Fox. Later, Yipao develops his skills further (and engages in some even more vigorous physical comedy) when he teams up and trains with a beggar who is blessed with impressive fighting skills; as played by director Sammo Hung, a genre legend in his own right, he is a man whose grace, speed and skill belie his bulk. It is here that Yuen really gets to show what he can do in an eye-popping ballet of fast, precise and gorgeously acrobatic martial arts moves, followed by an extended scene in which he leaps, hops and backflips over a skipping rope, pre-figuring the punch line of the climactic fight. By then the plot has essentially dried up and the comedy has been put largely on hold, paving the way for a first-rate three-way display of varied martial arts, the beggar's self-proclaimed 'mish-mash' style.

Held in high regard by many genre fans – Bey Logan included – Knockabout is very enjoyable stuff, the dumb-and-dumber comedy tending to grow on you as the story progresses and as it becomes increasingly integrated into the action. But the film moves into a different gear once Sammo himself takes a key role, really showing both Yuen's skills as acrobatic fighter and Sammo's own as both a performer and action director, all of which contribute to providing a final third that should satisfy even the most demanding genre fan.

Fully restored from a high-definition master, this is another fine transfer from Hong Kong Legends, some minor contrast inconsistencies in the night scenes being the only visible flaw. Contrast, colour and sharpness are otherwise impressive, black levels are generally fine, and there's barely a dust spot to be seen. The picture is framed 2.35:1 and anamorphically enhanced.

There are three soundtracks available: the original Cantonese mono, a 5.1 remix and the expected (American) English dub, also 5.1. Unlike many previous HKL 5.1 tracks, this really is a remix and an impressive one – separation is excellent, with very good use of the rear speakers (as you watch one fight, another audibly plays out behind you) and the sound quality surprisingly good. The English dub, as Bey Logan points out on the commentary, has its entertainment value.

Well if you've got this far you'll already know that there's a Commentary by Bey Logan, an almost inevitable but always welcome inclusion for a Hong Kong Legends release. As usual, Logan is loaded with information on the actors, the locations, the director and other related genre works, a fair few of which I have yet to catch. He barely pauses for breath here, even interrupting himself mid-sentence to comment on the on-screen action, translate the Chinese lettering on signs, and even talk about the food being eaten. An essential companion to the film.

The Trailer Gallery features the UK Promotional Trailer (1:42), which is for this very DVD and rare in that it has an English narration rather than being by the usual deep American Trailer Voice Man. The Original Theatrical Trailer (3:53) is anamorphic 2.35:1 and seems to have been restored with the same care as the main feature and is a very good sell.

Heavy-Hitter (7:09) is an interview with director, action choreographer and co-star Sammo Hung, who talks about the casting and the abilities of his performers, and reminds us that one of the pricipal appeals of Hong Kong actioners is that the actors can really do the moves and are not being faked by special effects. The interview was in Cantonese with English subtitles and in anamorphic widescreen, as are all the other extras except...

Above the Law (7:18) has actor Leung Ka Yan (who plays Taipao) talking about how he got into movies, how he learned martial arts and his experience of working on Knockabout. This one is non-anamorphic widescreen and has the film title stamped large over all extracts, suggesting an interview that has been bought in rather than recorded specifically for this disk.

Monkey Magic interviews Chan Sau-Chung, a master of monkey kung fu (yes, it's a real style). His story is almost the basis for a martial arts movie plot in itself, having learned kung fu in order to be able to defend himself after being repeatedly bullied at school. He provides a history of the monkey kung fu style and an outline of its techniques, and talks at some speed – look away for a moment and you'll miss three subtitles.

Back-to-Red (3:44) gets a mention on the commentary track and was the original intro to the film, a sort of overview of the techniques that Yuen was to use, performed against a plain red backdrop, an a common feature of martial arts movies of the time. There's also some comedy-action interplay with Sammo Hung. It's pretty impressive stuff, and framed anamorphic 2.35:1

Whether Knockabout is the masterpiece Bey Logan claims is very much in the eye of the beholder, but it's certainly a great deal of fun. Certainly if you can stomach the outrageous mugging in the first third there is a great deal to admire and enjoy, and the final act is worth the price of admission alone.

Hong Kong Legends have done it again with this DVD, supplying a fine transfer, an impressive sound remix, an information-packed commentary and some interesting extras. For martial arts movie fans, another must-have.

* He had previously worked as a stunt double on a number of films, including Bruce Lee's final film, Game of Death.