There’s an almost primal satisfaction in seeing a familiar face back on Saturday night television where they’ve always belonged. On this occasion, however, it wasn’t just the sight of Brucie cutting some capers which confirmed the world was turning on its correct axis.

A weekend appointment-to-view on and off for half a century, the return of Robin Hood – and to such a flagship place in the schedule – is, let’s be clear, worth celebrating in itself. And from the point of view of setting out stalls and proffering introductions, this first episode back on screen more than did its job, nimbly flitting between motive and impulse, and action and consequence.

Yet from the off it was thunderously clear this was no Errol Flynn gadabout. Here there was plenty enough back-story to shade Robin in more than just a Lincoln green wash of youthful piety.

Given the temptingly convenient option to sketch 12th century England as a simple struggle between good and evil or forest and town (step forward Kevin Costner), this was a striking move at so early a stage in proceedings. Social and geographical loyalties were blurred from the off. Lest anyone forget, boomed the implication, Robin is a nobleman, not a peasant; he has had a place reserved for him at the Sheriff of Nottingham’s table despite his long absence – an absence spent, incidentally, fighting for the establishment by way of supporting the King’s Crusades in the Middle East.

Various faces, some familiar and some soon to be over-familiar, then shuffled forth to assume their place in half-remember mythology. Look, there’s Marion pouting. See over there: it’s the Sheriff gurning. And there’s Guy of Gisborne, black of cloak and – of course – also of heart, snarling repetitively.

Yet none of this was done with heavy-handed exposition. Again, the episode’s pace and agility saw to it that the principal cast, along with their respective agenda, made their entrance minus hysterical melodramatics. Even Keith Allen, doing his best Keith Allen which can’t have been to anybody’s great surprise, was taken down a peg thanks to having to wear a stupid fluffy hat.

But from the point of view of imbuing the series with some momentum, of sufficiently winding up the show’s motor to send everyone and everything charging off into another 12 episodes, this first outing was not quite the powerhouse it should have been. Proceedings needed to burst forth with all-consuming, all-addictive energy, demanding you tune in again and again. Instead they half-shuffled off the starting grid, heading in the right direction but more through expediency than intention.

A reason for this was the presence, or rather the non-presence given his avowedly low-key performance, of Jonas Armstrong in the title role. Youth and maturity are not mutually exclusive qualities, but Armstrong, though undoubtedly blessed with the former, never seemed to muster enough of the latter to make him a credible leader of men. His eyes had just too much innocence in them to belie the substance of his deeds, at least in this first episode.

Casting against type doesn’t always spell trouble. Think of David Burke successfully playing a “young” Watson in Granada’s Sherlock Holmes, or the notion of Robbie Coltrane as a crime-busting super-sleuth. But here Armstrong needed to do just that bit more than run around and fire two arrows at the same time to indelibly stamp his take on this oldest of folk heroes. Hopefully he, as well as the show itself, will grow in stature over the forthcoming months.

An omen of sorts came within the last quarter of an hour, when all interested parties finally got down to some derring-do. Suddenly the story crackled into life and that which had only been frustratingly suggested so far – fear, tension, death and retribution – uncoiled with satisfying relish. Here was what you wanted: baddies blundering, crowds baying, nerves jangling. It was unashamed swashbuckling, marred only by the fact that Robin’s hugely irritating servant Much failed to be thrown off the top of a tower and plunge to his death. Still, when was the last time you saw people being hanged 10 minutes before Strictly Come Dancing?

Not the consistently superlative opening that it could and should have been, then, but a decent enough forward march, albeit one not entirely sure where precisely it’s going. Ratings-wise the episode certainly did the business (8.2m at the time of writing, though this will surely go up when videoed and delayed viewings are factored in), but you sense the show is going to have to work hard to sustain and renew its audience. There just wasn’t quite enough here to command you to tune in next week and the week after that and on all the way through to Christmas.

Perhaps it’s because, unlike its recent teatime antecedent, it doesn’t come with a gaggle of fandom already attached. Perhaps it comes down to whether you subscribe to the whole vaguely preposterous Robin Hood conceit or not. Throughout screen history the character has never been played by somebody particularly likeable, but in most cases that hasn’t mattered given the character is not particularly likeable anyway. It’s what Robin does and how he does it which catches the eye and stops the heart, not the man’s ability to state universal truths or crack a doleful pun.

If the notion of a man righting wrongs with a bit of capricious archery and a twinkling stare clicks with something deep inside you, then barring exceptional circumstances (Jason Connery) you’re always going to sign up to the man’s latest incarnation. If, however, you can’t get over the rudimentary dimensions of the Dark Ages and need to see your heroes engaging in philosophical battles over whether to leave someone behind in a parallel world or whether to flick a switch that could destroy entire life forms, you’ll never be able to see Loxley Wood for the trees.

Which is a shame, because this version of Robin Hood could well prove to be the most inclusive and unassuming piece of drama BBC1 has shown on a Saturday night for years.