Andy Duncan on Broadcasting

Should you really have to pay to see Desperate Housewives on your iPod?

Is any other business sector experiencing the same exhilarating rate of change as the global media industry? Barely a week goes by without an announcement of some fresh initiative that signals a further, irrevocable shift away from the passive, linear consumer behaviours that have sustained the industry over the first century of its existence.

In the past few days, both Channel 4 and BSkyB have unveiled plans for mobile TV channels, while ITV (risking a barrage of unkind Carlton and Granada jokes) is reported to have tabled a bid for Friends Reunited. In the US, CBS and NBC have announced deals that will allow cable and satellite subscribers the opportunity to catch up on their favourite prime-time shows on demand and free of commercials, from the day following their network transmission, for a payment of 99 cents per episode. The CBS and NBC deals promise to open up a new world of choice for American viewers. Alongside ABC's decision to make episodes of Lost and Desperate Housewives available straight after network transmission to users of Apple's new video iPod, it means that Americans have less excuse than ever before for missing their favourite television shows.

It will not be long before the majority of British households can enjoy similar, if not greater, freedoms. British broadcasters are also working on making on-demand catch-up TV services available across a range of new media platforms, most notably broadband and mobile.

The most heralded such service is the BBC's Interactive Media Player, on trial in thousands of homes and due for national launch at some time next year. Subject to the necessary approvals, the IMP will allow broadband users to download and watch any BBC TV programme from the previous seven days. Home Choice already offers video-on-demand (VOD) catch-up services to its small but growing customer base.

Channel 4 is working on its own plans to make its programmes available on an array of new platforms, with options on broadband and mobile well under way and a variety of other initiatives given the go-ahead, including allowing Sony PSP users to download one of our dramas before its Channel 4 transmission. Like the BBC, we ultimately aspire to offer our viewers a catch-up window on all our programming on broadband, mobile and other platforms.

There is, however, a key difference between how these services appear to be developing in the UK and the US, one that goes to the heart of the historical divergence between the two broadcasting cultures.

While US networks see only a fresh commercial opportunity in VOD catch-up, UK broadcasters, led by the BBC and Channel 4, also see a public-service opportunity to ensure that TV programmes remain available to all, regardless of how new viewing platforms develop. The BBC's IMP will offer its seven-day catch-up service free of charge to every British viewer, and Channel 4 is also assuming a first public-service window for any programme or service it launches. Unlike the US market, it is hard to see British broadcasters pursuing a pay-only route - although the expectation must be that all broadcasters and independent suppliers will charge viewers to access content after the initial public-service window.

Currently, Channel 4's ability to offer a similar service to the IMP is tied up in the forthcoming Ofcom Television Production sector review. This will look at the whole of UK production and will need to address the key issue of how to maintain a healthy independent sector.

Ofcom will have to decide on a range of complex rights issues in the first half of next year. As part of that review, Channel 4 is asking for a 30-day public-service window to offer its content on new platforms.

While we continue to fully fund the vast majority of our programmes, and take all the financial risk, we believe we need a window of this length to allow us time to recoup our creative investment and deliver our remit to audiences via whichever device they choose.

At the heart of British television's culture of public service is the tradition of high quality programmes and the principle of free access to all. Both tradition and principle must be protected as the migration to new viewing platforms gathers pace.

Harry's last and greatest Test

I didn't know Harry Thompson well. Recently, I was lucky enough to spend a day with him at The Oval during the last Test of England's epic Ashes series against the Australians. Cricket was one of Harry's passions, and I'm pretty certain he felt as excited and privileged as the rest of us to be present at the closing stages of such a hard-fought and overdue Ashes victory for England. Like that series, Harry's programmes and his huge contribution to television will stay in the memory. From The 11 O'clock Show and Da Ali G Show on Channel 4, to Have I Got News for You and They Think It's All Over on the BBC, he has left an indelible mark on the recent history of British television. Anyone who believes in creative, high-quality TV will mourn Harry's untimely death a week ago and the passing of his talent.

Andy Duncan is chief executive of C4

Greg Dyke is away