BBC shows including Sherlock, Doctor Who and Top Gear will soon be available to watch for up to 30 days after first transmission on online video service iPlayer, giving viewers an extra three weeks to catch up with their favourite shows.

The BBC will extend the amount of time its programmes are available on its iPlayer video-on-demand service from seven to 30 days after the proposals were approved by the BBC Trust, effectively quadrupling the amount of content on offer.

iPlayer, which had a record 3 billion requests for TV and radio programmes last year, with a top 20 dominated by BBC2's Top Gear, will make the change to its catch-up window in the summer.

However, a further change will mean some programmes are actually available for less time, with an end to the "series stacking" option that enable viewers to download all episodes of a series retrospectively.

While the amount of TV programmes available on the iPlayer will increase fourfold, the total amount of radio content will increase around two and a half times.

Diane Coyle, vice chairman of the BBC Trust, said: "With an average of 10.7 million programme requests every day, BBC iPlayer is highly valued by audiences and has been a phenomenal success since it launched six years ago.

"It is important that iPlayer continues to evolve and meet the expectations of users. We have conducted a thorough assessment of these proposals, including taking independent advice from Ofcom, and concluded that this is a sensible move that will benefit audiences and provide a clearer and more consistent catch-up service."

In a statement, the BBC said: "People keep telling us they want programmes to be available on BBC iPlayer for longer – so extending availability from seven to 30 days will make iPlayer even better.

"New iPlayer already has downloads, better recommendations, HD, live restart, favourites and collections, and extending the catch-up window to 30 days gives people even longer to enjoy their favourite BBC programmes. We will now set about making this happen with the aim to roll this out from the summer."

'Front door' to content

The overhaul is part of BBC director general Tony Hall's ambition to transform the iPlayer into a "front door" for the entirety of the BBC's content, rather than a catch-up service aimed at people who missed a particular programme.

Last month, Hall announced plans to axe the BBC3 TV channel and make the 11-year-old youth-orientated service online-only.

Media regulator Ofcom said the extension was likely to mean people spent less time watching programmes from commercial broadcasters because of the increased amount of time they spent on the iPlayer.

"There is a finite amount of TV viewing time available," said Ofcom in a report on the potential market impact of the change. But it said the impact on commercial broadcasters was "unlikely to be material".

However, Ofcom warned that the cumulative effect of changes to the BBC's online and on-demand offering, including plans for a pay-digital service, BBC Store, may be greater than the sum of its parts.

"We note that the BBC is considering wider strategic changes to BBC Online and iPlayer, including the proposal for BBC Store," it said.

"While these potential changes are not within the scope of this assessment, the trust may wish to consider whether there will be a cumulative impact on other operators resulting from the changes, when taken as a whole, which may not be captured when each change is considered on a standalone basis."

Switch from commercial content

A BBC-commissioned report by consultants Mediatique said an extra 53m hours of on-demand viewing would switch from commercial content to the iPlayer as a result of the change by 2018. Although the number sounds biglarge, it would equate to only 0.1% of total catch-up viewing.

Mediatique said the change would mean an extra 375m hours of content viewed on the iPlayer by 2018, a total of just under 10bn hours of programmes accounting for 11% of all BBC TV viewing.

It said 144m fewer hours of recorded programmes would be watched on viewers' personal video recorders as a result.

Ofcom disagreed with the BBC's claim that any decline in linear TV viewing would be from its own channels, saying it was "less reasonable" to say there would be no impact at all on commercial services, especially a broadcaster such as UKTV which relies heavily on BBC content.

It also said the BBC had failed to take into account the potential impact on subscription video-on-demand services, such as Netflix.

However, the regulator said the effect on live TV would be "relatively small".

Catch-up radio listening on the iPlayer will increase by an estimated 14m hours a year to 169m, with on-demand accounting for 1% of total BBC radio listening by 2018.

The effect on commercial radio, with the BBC already the dominant player, is expected to be minimal.

The TV catch-up extension will also lead to a further drop in BBC DVD sales, but Ofcom said the market was already in decline and the impact was likely to be small.

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