EastEnders live, BBC One

It was Stacey whodunnit. EastEnders’ first live broadcast last night, to celebrate 25 years on BBC One, ended with Stacey Branning (Lacey Turner) declaring, “It was me. I did it. I killed Archie. It was me.” So now we know, as one of the most drawn-out storylines in the history of soaps finally reached its conclusion (Archie Mitchell was killed at Christmas).

Only it didn’t, because next week’s episodes (which were pre-recorded as normal, with dual storylines to cover all 10 suspects' possible guilt or innocence) will explain why Stacey done it, as they say in this mythical part of east London. But at least we now know the “who” and are about to learn the “why”.

The BBC also drew out the in-house pre-publicity for this special episode, and much of it was enjoyably inventive. Last night’s episode began with colourful, redrawn opening titles and earlier in the week one episode ended with a medley of fans humming the show’s theme. There was an entertaining walk down memory lane with a show about the “doof doofs” (EastEnders’ final scenes end with the "doof doof" intro of the closing theme) and snippets were shown between BBC One programmes of fans guessing who killed Archie Mitchell (Larry Lamb), the second owner of the Queen Victoria (“the Vic”) to be killed among the optics (Dirty Den being the other).

The live show was an inspired idea and must have garnered a good proportion of the 16.6 million viewers who watched yesterday evening. I must confess I prefer Coronation Street (ITV), with its wonderfully camp northern humour, to the grittier, shoutier EastEnders. Whenever I dip into EastEnders I find the characters spend an inordinate amount of time shouting at, menacing or threatening each other, and E20 a place where smiles are in short supply; I live in London so I don’t wish to see my daily bus journey repeated on screen.

EastEnders started life with the working title “E8” - its fictional setting, Walford, is now designated E20 - and was the brainchild of producer Julia Smith and script editor Tony Holland, both sadly now no longer with us. The first transmission was 19 February 1985, hence last night’s anniversary, and back then the soap was shown twice weekly, with an average audience of 17 million. It’s now broadcast four times a week, and averages between 10 and 11 million viewers

It was the first and remains the only southern soap, and has always prided itself on its social realism, but the picture it paints of the East End couldn’t be more wrong. EastEnders is, a few characters notwithstanding, hideously white (the East End, long a home to various immigrant settlers, is now predominantly Asian), and the thuggish criminal element once associated with it through the Krays (here the Mitchells) has long since moved out to the suburbs. And I know London can be a dangerous place, but Walford’s murder rate is ridiculous.

Which is where we came in. Executive producer Diederick Santer must have been very relieved no one dried up or corpsed and that last night’s episode went off relatively trouble-free. It was an enormous operation - it took nine months to plan, and involved 36 cameras, 10 sets, 51 cast members, 13 make-up artists, 12 dressers and 16 props people. The episode is Santer’s swansong, as he will shortly leave EastEnders to take up a role elsewhere in the BBC.

Was it worth it? Probably not in terms of the cost (I suspect the BBC Trust are asking for a budget breakdown as I write) and also in terms of dramatic tension; if ever you wanted to illustrate the importance of good editing, the rooftop chase where Bradley Branning (Charlie Clements), Stacey’s husband, fell to his death would be a good place to start. In fact the only tension in the show (apart from waiting for the last-scene reveal, of course) was in wondering who would cock up first, the actors or the crew. That prize went to Scott Maslen as Jack Branning, who stumbled badly over his first lines but recovered later in the show, but the camera also wobbled in a couple of places so I would call it an honourable draw.

But in terms of delaying the denouement and giving real viewing pleasure, it certainly did work. It’s rare for any soap storyline to stay a secret (either because TV companies want pre-publicity, or insiders reveal them to the media) and nobody - not even the bookies - knew whodunnit before transmission. Indeed Turner herself was told only 20 minutes before EastEnders went on air. So simply for the rare, genuine suspense involved, last night was a treat.