The Weekend's TV: There's plenty to admire under the bonnet

Cranford, BBC1; Blair Years, BBC1

Ignore the wrapper. Cranford begins with the kind of winsome credit sequence that might have you leaping for the channel changer - a Posy Simmonds country panorama, accompanied by animated curls of smoke from the chimneys and a Carl Davis score that perfectly captures the inoffensive prettiness of mediocre costume drama. It is all tea-and-crumpets reassurance, and has you bracing yourself for a triumph of heritage cosiness. And then the first scene showed you dust sheets being hauled off the furniture in a flurry of preparation for a new guest and you were plunged into the thing itself, which is as tart and vital and inventive as you could wish. What the creators have done, drawing on two novels and an extended short story, is to produce a kind of Elizabeth Gaskell mash-up, shuffling storylines around and swapping destinies to create their own Cranford, essentially true to the original but in a way that may well have purists yelping in alarm. It is a little more sentimental than the original, perhaps, but the sentiment is so skilfully poised against the social comedy that rather than being cloying it surprises you into deeper feelings than you might have expected to bring to a bit of historical escapism.

It also has a luxury-selection cast, an absolutely delicious assortment of British character actors, some hard-centred and some soft, nestled in rustling pleats to be picked out one by one. Eileen Atkins and Judi Dench are effectively the headliners as the Jenkyns sisters, Matty and Miss Deborah, with Imelda Staunton bustling up close behind as Miss Pole, Cranford's human internet, who can be relied upon to convey the smallest crumb of gossip from one end of the high street to the other almost instantaneously. Jim Carter also has a lovely role as Captain Brown, a retired military man who Gaskell kills off pretty quickly but who has been has keptalive here. And then, just as you think the series has shown off all it has to offer, you discover another layer of treats underneath. Lesley Manville turned up as the housekeeper to Harrison, the new doctor. Francesca Annis got some tellingly ingenuous lines as the local aristocrat, and Michael Gambon made a promising appearance in the credit-sequence trail for next week's episode.

Our introduction to Cranford is by means of Mary Smith, taking refuge from domestic trouble in Manchester with the Jenkynses, and helpfully being inducted into Cranford's rigid code of the done thing, which can make even the eating of an orange into a social minefield. "My sister does not care for the word 'suck'," explained Matty timidly, after Mary had impulsively revealed her favourite way of eating the fruit. "We will repair to our rooms and consume our fruit in solitude," Miss Deborah announced glacially. True to the character she plays, Eileen Atkins extracts every last drop of juice from this role without any vulgar slurping, often making you laugh out loud by an almost indistinguishable congealing of her features. When Captain Brown overstepped the mark by giving her a copy of Charles Dickens's The Pickwick Papers (Miss Deborah prefers Samuel Johnson and models her letter-writing style on his prose), she looked at the book as if she'd just been handed a dead frog. In scene after scene, a comedy that is present in Gaskell, though not always obvious, is skilfully lit to bring its contours into sharper relief. It is a distinctively Northern comedy, too, almost Bennettesque in its agonised calculation of social standing.

Heidi Thomas, the writer, has also preserved the important sense in Gaskell's writings that this matriarchal society is on the brink of huge change. This is a world in which one of Cranford's luminaries can still be carried down the high street in a sedan chair, but which the railway line is just about to reach. It's also a world in which the aristocratic Lady Ludlow can dismiss a girl as unfit for employment because she's had the audacity to teach herself to read and in which a broken arm can threaten a working man with starvation. The tiny catastrophes of the genteel - a cherished piece of lace being swallowed by the cat or the wrong kind of people moving in next door - absurdly loom larger than the real agonies of the poor, though we're never allowed to forget the latter. Beautifully played, very funny and deftly directed, it's a world I can't wait to get back to.

The new three-part series The Blair Years contained at least one modest scoop: a No 10 strategy document in which Tony Blair's advisers bullet-pointed the appointment of "the new Chancellor", noting that whoever moved in next door should have a "lack of personal investment in previous policies". But it's still just too early for the interviews with Blair to really deliver revelations. Confronted with solid evidence of interdepartmental sulks and scheming, he does the Blair blink and stonewalls: "It's not helpful to do that, not when he's sitting there doing the job now." Be patient, my pretties. One day he'll tell the whole truth.