Talk about milking the golden calf! The BBC had a popular drama series called Life on Mars, in which a police inspector was transported back in time to 1973, where he conflicted with the old-fashioned police methods of his boss, Det Insp Gene Hunt. As that time-traveller committed suicide at the end of the series, there was no way of having a sequel . . . unless you introduced another character who was also taken back in time. Thus Ashes to Ashes (BBC1) was born, with Keeley Hawes as DI Alex Drake finding herself mysteriously back in 1981 and again coming into conflict with Gene Hunt (played with relish by Philip Glenister).

It makes little sense unless you saw the previous series and even then it makes little sense, especially as the original police team doesn't seem to recognise that it is going through the same experience as last time. Every ten minutes, Alex Drake has a flashback or a dream from which she awakes with a start, panting heavily. She also talks in unconvincing psychological gobbledegook, using words like dystopia and referring to her fellow police officers as "conscious recessional forms". I imagined that one day I might see a credible cop drama on TV, but it was just a dream.

Timewatch took us back to the fifties and sixties with a documentary called Ten Pound Poms (BBC2), about the million Britons who emigrated to Australia after the war, lured by the thought of paying only £10 to move to a country which seemed sunnier and more promising than the UK. Elizabeth Britton thought it was "a welcome chance to escape the desolation of postwar Oxford".

At Australia House, prospective emigrants were shown enticing films about Australian life (as true-to-life as army recruiting commercials). Some of the people who emigrated found that Australia was not everything they expected. One family moved into a house infested with cockroaches, while others were billeted in Nissen huts until they could buy their own houses. Discontented newcomers were nicknamed "whingeing poms" and a quarter of the emigrants returned to Britain. Only white Britons were encouraged to emigrate, because of the 'white Australia' policy which excluded black or Asian people as well as the mentally handicapped.

I have never been into drugs much, except for music and television. Nonetheless it was educative to watch Horizon (BBC2), which examined some of "the most widely abused substances" and arranged them in a Top 20, ranked in order of harm. Of course, drugs are a contentious issue. One man said: "All of them are dangerous." Another said: "The illegality of drugs makes them dangerous." But the scientists took care to look scientifically at the facts about drugs, using three different criteria: their effect on individuals, their addictive capacity, and their social effects. The results were revealing.

As you might expect, the two most dangerous drugs are heroin and cocaine. But many drugs classified by legislation as Class A drugs (the worst sort) turned out to be less hazardous than some in Class B or C. Ecstasy and LSD, for example, are Class A drugs but they were only rated 18th and 14th in the list, below valium and cannabis (which came in at nos. 7 and 11 respectively).

"The most deadly drug in the UK" is tobacco (at No. 9), which kills 114,000 Brits every year - more people than die from "drugs, alcohol, HIV, suicide, homicide and car crashes combined". Another legal drug, alcohol, was even higher in the list: at No. 5. It causes 40,000 deaths per year (fewer than tobacco) but it has 40 million users in Britain and it has very harmful effects on society, particularly the NHS.

Last Friday, BBC4 devoted a whole evening to jazz - including two and three-quarter hours about Oscar Peterson, one of the world's greatest pianists. It was a wondrous event, because jazz seldom gets on TV nowadays. Mind you, these programmes were probably only scheduled because Peterson died recently.