Once more the celebrities enter the Big Brother House to the cherished and almost timeless cries of “Who?” and “Which one is she again?” If anything, those cries have sounded even louder and more wounded this year.

To complain about this, however, is to betray a twofold misunderstanding - first about the nature and intent of the Big Brother project. The obscurity of the contestants is frequently used to whip the producers of the show for a perceived failure. The assumption seems to be that they would have been doing their job better had they secured the participation of, say, Barack Obama rather than, as it happens, Tommy Sheridan.

But the Celebrity Big Brother format depends for its pleasures - take them or leave them - on the spectacle of people generously handed one last blow on the dimly glowing embers of a career, and the next president of the United States clearly would not, at this juncture, deliver the rich chemistry of neediness mixed with lifelong disappointment that the show gleefully thrives upon.

Similarly, it's Latoya Jackson this year, and not her brother Michael - and quite deliberately, one feels sure. If the Big Brother sitting room after supper resembles a branch of Woolworths, two days from closure - brightly lit and yet hauntingly bare - that is the point.

De-listed

Second - and by extension - there can be no justice in the often repeated quip that the use of the word celebrity in the title Celebrity Big Brother represents some kind of “offence against the Trade Descriptions Act”. To suggest as much is to ignore the radical shift in the meaning of the word celebrity - a linguistic change that shows such as Celebrity Big Brother and its al fresco sister I'm a Celebrity... Get Me out of Here! have led the way in bringing about.

Once narrowly and fussily confined to a small and precious elite of high-achievers, “celebrity” is now a splendidly elastic term that can be deployed without stretching to encompass backing vocalists, resting spear-carriers from provincial theatre and cricketers' girlfriends. Therefore tiresome qualifications such as “so-called”, “B-list”, “C-list” and so on, all the way through to “Z-list”, are redundant, as is the snooty practice of tweezering the word between inverted commas for derisive purposes. In 2009, “so-called” is understood within the meaning of the term celebrity, and its use is officially a tautology.

Anyway, now we've got that straight, which celebrity are you backing this year? My money's on that bloke. You know the one. Thingummyjig.

Before-his-time lord

When people aren't complaining that the Big Brother celebrities aren't famous enough, they're grumbling that the new Doctor Who is too young. “Toddler in the Tardis”, warns a dismayed posting on a BBC messageboard. True enough, Matt Smith, ceremonially unveiled over the weekend as the successor to David Tennant, is only 26 - the most junior doctor ever. Doctor Who, on the other hand, is 903, making an 877-year discrepancy, if you are going to be picky about it. Which people clearly are. Some are suggesting it should have gone to an actor with more suitable amount of experience, which, if you wish, you can interpret as a subtle way of saying Bruce Forsyth.

You could hardly announce a new Doctor Who without upsetting someone, though. The Time Lord is the most iconic figure on contemporary television. After Simon Cowell, of course. What should encourage the doubters is that Smith says he “hasn't slept” since he was told he had got the job, just before Christmas. Remember, he isn't even due to snatch up the Sonic Screwdriver until 2010, after Tennant “regenerates” in the 2009 Christmas special. A full year of sleeplessness on, with sagging eyelids and a few tired lines between those pastry-cutter cheek-bones, he'll be fine.

Amazing thing, though, regeneration. And, in a way, it's what the contestants on Celebrity Big Brother are hoping for, too. The one with the dark hair, especially. You know - the one who was in a soap. Or was she a singer? That one.

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