The Weekend's Television: Doctor Who, Sat, BBC1<br/>Ashes To Ashes, Fri, BBC1

He travels in style

New series of Doctor Who, new Doctor, new chief scriptwriter. This is a big moment in the pop cultural calendar, so take a deep breath.

Stepping into the Doctor's shoes this time around, in case you've been living on Gallifrey for the last year (Earth time), is Matt Smith, who sprung to fame playing an overly earnest Labour Party apparatchik in 2007's Party Animals. He's since been introduced to the public via a well-placed publicity campaign as someone running around in a tweed jacket, bow tie and ankle boots. It's a blend of old and new – this is, after all, someone who travels across the galaxy distributing witticisms that wouldn't have been out of place in the 1960s – that is entirely appropriate.

The other key player making their debut on Saturday night was the new chief writer, Steven Moffat. He's clear about where he's aiming his creative sonic screwdriver. "For me, Doctor Who literally is a fairy tale," he said of the new series last month. "It's not really science fiction. It's not set in space, it's set under your bed. It's at its best when it's related to you, no matter what planet it's set on."

The first look we got at all this newness was through some expensive-looking, genuinely exciting pre-titles. Smith was initially introduced hanging out of the Tardis as it sped across a familiar-looking London skyline. An impressive start, one that grabbed you by the lapels and screamed "THIS IS AN EVENT" (let's hope, incidentally, that George Osborne wasn't watching such scenes while making notes with a big red pen) before we'd opened the storybook's first page. We're greeted with the sight of nine-year-old Caitlin Blackwood as Amelia Pond, an orphaned Scottish girl living in the West Country who was scared about a crack in her bedroom wall and the strange noises emanating from behind it. Along came the Doctor, and the next few minutes were played for laughs, as he tried various types of food and spat them across the room. Once that was finished, and we were all familiar with this crazy new guy who wasn't David Tennant, we got into the story proper: the Doctor promised to come back in five minutes, but spent over a decade in mind-warping space-time-world, and returned to find Pond all fully grown. She was now filling the potentially titillating shoes of 22-year-old Karen Gillan, who was introduced with a lingering shot up her thighs. Subtle. Then it turned out that the noises from behind the wall were due to the guards of an alien prison, the Atraxi, saying that one of their inmates had escaped. An evil shape-changer had wormed through the crack into the Ponds' house, and the prison guards threatened to destroy Earth if they weren't handed back their misplaced convict.

If you're looking for something cutting edge, this has all been seen before. The Douglas Adams-esque threat of the world being demolished for some spurious, bureaucratic reason; the 24-style rush against the clock; the Buck Rogers-type mess made out of time travel. Where it does win through, however, is in Moffat's dialogue. The famous British tongue-in-cheek gets our heroes out of many a scrape, our scriptwriters, doubly so. When telling Pond to make him some different food, the Doctor told her to "fry something, you're Scottish". When discussing the crack, he said, "you've had some cowboys in here. Not actual cowboys, though that can happen". There were plenty of jokes about camera phones. It was better on screen, honest.

As for Smith, it's too early to say how he'll fare, though he equals Tennant's over-the-top eccentric, devil-may-care manner very well. He throws things around a lot when he could hand them to people, for example. Tennant seemed to be loving all the attention slightly too much by the end, so Smith's appearance is welcome. And while cynical hacks might dismiss this as more of the same, I would imagine eight-year-olds will love it, which is much, much more important.

From one sexy time traveller to another. It was also the welcome return for a third series of the Life on Mars spin-off, Ashes to Ashes, on Friday night. In case you're not up to speed, the show sees female Metropolitan Police officer Alex Drake (Keeley Hawes) shot in 2008 and inexplicably regaining consciousness in 1981, where she's working for Detective Chief Inspector Gene Hunt (Philip Glenister). As viewers of Lost will appreciate, a law of diminishing returns applies to scripts that rely on "what the hell is going on?" ambiguity for endless dramatic twist after endless dramatic twist, and that's certainly the case here. Hunt is slightly less of an amusing anachronism than he used to be, and people have more of less worked out that the full truth will always be unforthcoming. This episode saw Drake awake back in 1983 after being shot by Hunt at the end of the last series. Now Hunt's got a morally ambiguous discipline officer, Jim Keats (Danny Mays), on his back, as well as a kidnapping to contend with. Doesn't match up to the glory days of Life on Mars, but it's still top telly.