It always took a half dozen or so episodes for a new Doctor Who to comfortably pigeonhole themselves by way of a signature quirk: “the grumpy one”, “the young one” and so on. Christopher Eccleston is no different – except for the fact we’re six episodes in and he’s still just “the new one”.

It’s hard to think up anything else, to be honest, because all the stories in the series so far, while thoroughly entertaining and undeniably memorable, haven’t really shown off the Doctor at all. Instead he’s come over as a sort of Inspector Gadget figure: blundering into situations, charging around a bit, then doing little – if anything – to resolve problems which have arisen, being saved by chance, coincidence and the foresight of his colleagues.

Granted, to begin with this didn’t really matter that much, as the show was mostly concerned with the re-introduction, after a couple of decades off screen, of all the familiar components of Doctor Who: the TARDIS, a companion, the idea of aliens. Exciting stories with beginnings, middles and ends, and the Doctor’s role in charting a route through them, weren’t the most important thing.

As time’s gone on, however, the role of the Doctor, or rather the lack of it, has loomed unavoidably into view. Last week his chief contribution to averting catastrophe was to remember the name of a planet. This week he didn’t even do that, merely pressing a “Enter” key a couple of times and expressing delight at unearthing a giant bazooka. Other people are saving the world. Other people are finding clues, taking risks, seeing sense. They’re doing it very well, of course, and in a way that makes for great TV, but it can’t help leave Christopher Eccleston looking increasingly superfluous.

He started off being a Doctor it wasn’t easy to warm to. Now he’s in danger of becoming one it’s difficult to respect or even find that interesting. Über-fans may dictate this is all to the good: the Doctor’s supposed to be alien, don’t you know, and hence behave accordingly. But that’s missing the point. The Doctor embodies humanity. He’s a hero to humans. He’s also supposed to be the hero of a children’s TV show. Acknowledging as much more than once in a while is crucial, or else the whole project begins to seep credibility.

Pulling another toothy grin and shouting a lot isn’t the answer; the last actor who tried playing the Doctor that way ensured the programme didn’t return for 16 years. But at least Sylvester McCoy’s pantomime Doctor appeared to think for himself and had a sense of timing. Christopher Eccleston’s Doctor would do well to become more than just a somewhat unfinished pastiche of Christopher Eccleston-not-being-his-usual-TV-self. He ought to do it pretty fast. He’s out the door in seven weeks time.

Yet the irony is that all of this – so far – hasn’t spoiled the entertainment value of the series in the slightest, precisely because the Doctor has been so unimportant. Every single week he’s been upstaged. Usually it’s by Billie Piper. During the Charles Dickens episode it was by both Billie Piper and Simon Callow. This week he was roundly played off the screen by a Dalek, by Billie again, by a spectacular sequence of mass slaughter, and by a shaft of sunlight. Meanwhile all his alien powers did nothing to either identify or resolve the Dalek’s menace. His main contribution was putting his cohort’s life in danger – again.

It’s important to stress how this didn’t, on balance, hinder the episode’s success. Rather it’s something that remains, at the moment, neither a curse nor a blessing, more a growing irritation. The arc of this particular story, from companion Rose’s initial encounter with the Dalek right through to her ordering it to commit suicide, was by turns intriguing, chilling and moving. A pity the Doctor wasn’t involved, but there you go. He was busy being strung up on an electrified crucifix, something he could have avoided if he’d shut up, but at least it seemed to bring him partly to his senses.

Having the entire episode hinge on the sidekick rather than the main protagonist is a nice twist, but it’s now happened several times in a row and if it goes on will only reduce the Doctor’s eminence even further. A Dalek outtalked him this week – that’s not right. You can’t help feeling pleased that it’s Billie who’s signed up for another series, not Eccleston.

Indeed, rarely has Doctor Who‘s prominence in the public consciousness relied so little on the bearer of the eponymous title. Most weeks it feels like it’s been anything but Eccleston that has been driving both the Beeb’s giant publicity machine or the nation’s workplace chatter. This time round there was a palpable sense the prospect of a flying Dalek was proving far more interesting to columnists, reviewers and listing magazines than what the Doctor was going to do about it. If the talk of the playground is running on the same lines, perhaps it’s as well regeneration – or whatever the programme-makers chose not to call it – isn’t far away.

Speaking of which, there can’t be many in the country who don’t know what a Cyberman is. In the words of Clive James, we don’t need a lolly to suck. It would’ve been welcome to give us some credit, and give the metal goon some dignity, by for once calling something by its proper name. The policy of not letting too much earnest continuity clutter up the stories had been working well, but in this instance the Doctor’s reluctance to say the one word that was probably on most viewers’ minds was churlish rather than charitable. It also made him look dumb.

Meanwhile for a show that was once nearly cancelled for being too violent, the extended scenes of carnage in this episode were by any measure eye opening. The fantasy element ensured they weren’t exploitative or gratuitous, but it still added up to a grisly display. The Dalek’s calculating and ruthless logic behind setting off a sprinkler system in order to electrocute everybody was far more persuasive than watching it take 10 seconds to download the entire internet, as was the way the rather crap flying (why was it so slow?) was offset by the icy blue light in its eyestalk.

This was easily the gloomiest episode since the series began; it also took place in real time. Both factors helped the show to rise still further above the equivocal contributions of its supposed star. But while it’s great that Doctor Who has proved it can flourish on a Saturday evening again, and as television which everybody feels permitted to watch and enjoy, two things have really carried it to date. The first is sheer momentum – a dynamism stoked by public interest and the urgent, restless attitude of the programme’s makers and its supporting cast. The second is the fact that every single one of the stories up to now could be boiled down to a simple, catchy riff: the first episode; the end of the world; Charles Dickens turns up; aliens in Downing Street; the Daleks.

Next week’s is the first to be missing any such hook. There was no obvious theme, or villain, or indeed plotline in the usual pre-credits trailer. In fact the clips were pretty incomprehensible. Next week is also the halfway point of the whole series: as far from the first episode as we are from the end. A suitable moment, then, for Doctor Who to get off his arse and do something. It is the name of the programme after all.