Casanova (BBC3); Supervolcano (BBC1): IF what writer Russell T Davies has done to Doctor Who is as good as what he's done to Casanova then we're in for a good time when the Time Lord returns later this month.

First, let's welcome Casanova in Davies's funny, sexy, bawdy new three-part series about the famed 18th century lover. This is a fast and furious fumble through various undergarments in search of the motive behind his randy behaviour.

As a child, he's introduced to rumpy-pumpy after stumbling across his actress mother having sex backstage. Like mother, like son. As he hops from bed to bed, he makes no apology for his actions. "If you could do what I can, you would do it too - but you can't," he says.

David Tennant is an actor, last seen in BBC1's Blackpool and with a wealth of stage work behind him, who's always been threatening to become a star. Casanova should finally establish him as such with a dazzling performance full of charm and wit. Peter O'Toole lends gravitas as the older Casanova, whose writings provide the excuse to recall his past seductions.

His early conquests include a threesome with sisters and a castrato who's not all he/she seems ("you show me yours and I'll show you mine," says Casanova), while Henriette remains tantalisingly unobtainable and engaged to his archrival Grimani.

The production looks absolutely fabulous and sounds as unstuffy as a costume drama can be without being ridiculous. If Davies has applied the same formula to Who's return, fans of the doctor need have no worries.

Last summer's The Day After Tomorrow was the mother of all disaster movies so I don't know why the BBC, with a smaller budget and less starry cast, try to outdo that with Supervolcano.

This is one of those factual dramas in which fictional characters are at the centre of events based on fact. Yellowstone Park in the US seems to have cooperated in the production, which is odd as the two-parter is a very good advertisement for not visiting this home of steaming geysers and bubbling mud.

Scientists reckon it's only a matter of time before the vast reservoir of red hot molten rock below the park explodes. The result will be the eruption of the biggest volcano in the world.

Viewers have no reason to remain in the dark any more. Experts in the film helpfully built a 3D computer model into which they fed all the facts, then stood back and watched in alarm as the whole park erupted.

Various personal dramas were played in an effort to make us care about the people involved. When chief scientist Rick Lierberman put his wife and child on a plane to England, you knew that something was going to blow big time. Happily, he remained to explain everything as it happened with talk of "seismic wave propogation" and "hydro-thermal event". There was a reporter to cause panic, while government spokespersons issued misleading statements as the arguments raged whether a catastrophic eruption was real or remote possibility.

Despite all the computers and hi-tech equipment, the old-fashioned warning signs were more reliable. Seeing the mass stampede of animals from the park, someone rightly predicted, "This is going to be big".

Published: 14/03/2005