Still, the speculation kept us occupied while we awaited this head-spinningly brilliant fourth series finale, which went out not just with a bang but with several explosions, a huge emotional wallop and the satisfactory tying-up of a number of long-running plot strands.
The Doctor did indeed regenerate, but only back into himself, by channelling his powers through his amputated hand, which was lopped off during the 2005 Christmas episode and has been sitting in a pickle jar aboard the Tardis.
The by-product of this was that when Donna (Catherine Tate) touched the jar, she created a half-human doppelganger of the Doctor, while also absorbing some of the Doctor's power and 900-plus years of knowledge. Naturally, it couldn't last, because there's only room for one Doctor.
When Davros and the Daleks were defeated in a thrilling showdown featuring past assistants Rose (Billie Piper), Martha (Freema Agyeman), Sarah-Jane (Elizabeth Sladen) and the entire Torchwood team, the Doctor had to face the fact that Donna's human brain would implode under the weight of being a part-time Time Lord.
In a shamelessly heart-rending tearjerker of a scene, he wiped her memory clean of everything that had happened since they met and returned her to her dreary old life on Earth.
Rose, meanwhile, more or less got what she'd always wanted: to spend the rest of her life with her beloved Doctor. She and the Doctor's doppelganger returned to her parallel Earth. At the end, the Doctor ended up the way he always ends up: alone and the loneliest being in the universe.
Written by Russell T Davies, the man behind the successful regeneration of Doctor Who, this was quite possibly the best episode so far.
The Conspiracy Files, BBC2's overheated documentary series, looked at the strange case of WTC 7, "the smoking gun of 9/11" -- an unfortunate image, I thought, given those horribly memorable TV news pictures of people fleeing through the streets to avoid billowing clouds of smoke.
WTC 7 was the third building to collapse on 9/11 and the one that everyone, except the conspiracy theorists, tends to forget about.
The official explanation is that it collapsed because of fire (it was only 350ft away from the North Tower and struck by falling debris) but the conspiracy theorists believe it was deliberately destroyed by a controlled explosion, engineered to destroy the evidence that the Bush administration plotted and carried out the 9/11 attacks.
A lot of it sounded convincing, too, until you heard the more convincing rational explanations. The biggest mystery the programme threw up was why conspiracy theorists tend to be twentysomething American males wearing hoodies.
Heat is yet another new food porn series from RTE1. Two chefs, the Kevins Thornton and Dundon, coach a pair of novices to take charge of a kitchen restaurant for a single night.
It's Ramsay-lite, as watery and flavourless as the coddle one of the novices tested out on passers-by. No thank you, I'm stuffed already.