BBC profits from new commercial approach as 'Blue Planet' proves a worldwide winner

Sir David Attenborough's Blue Planet series has become a multimillion-pound marketing phenomenon for the BBC thanks to an aggressive campaign to boost revenues through commercial spin-offs and foreign sales.

The series, cited as proof by the BBC that it can create quality programmes as well as chase ratings, has already pulled in £15m in retail and television revenue – more than twice the original £7m investment in producing it.

Even before the first programme was broadcast on BBC1 on 9 September last year, BBC Worldwide, the retail arm of the corporation, was gearing up to capitalise with a range of products from books to CDs to DVDs and a plethora of related merchandising.

Next weekend up to 10,000 people paying £15 a head are expected to gather in Hyde Park, central London, for the Blue Planet Prom in the Park, in which the score will be performed live to the accompaniment of footage, some previously unseen, from the series.

George Fenton, the composer who won Ivor Novello and Bafta awards for the music, will conduct the BBC Concert Orchestra while Sir David narrates. The idea of a concert was tested at the Royal Festival Hall in London last October, when 2,500 people paid £25 a head for a similar mix of choir, orchestra and narration.

Blue Planet proved to be the fourth most popular BBC programme of the year, with an audience peaking at 16 million.

So far it has been sold to more than 50 countries, becoming the number one show on American cable and winning more than half the total television audience in South Africa.

Last week the BBC secured for the first time a £350m borrowing limit from the Treasury specially to develop its commercial arm. The Blue Planet has provided an example of how future commercial projects may look.

To maximise returns, the series was marketed at both adult and child audiences, with books ranging from sticker books to specialist volumes on extraordinary fish and killer whales. The main illustrated volume won a prestigious British Book Award.

Sales revenue in Britain alone has reached £2.8m with only Delia Smith's third How to Cook book doing better out of the entire BBC booklist. Sales of the adult books have made more than £3.2m overseas. On top of that, The Blue Planet has proved a solid seller on video, at £29.99 for the series, and DVD at a price of £34.99. The video is available in 25 countries and was one of the BBC's top five of the year.

Alix Tidmarsh, BBC Worldwide's head of intellectual rights, said the series had captured people's imaginations with its "wondrous" images of the magic of the sea. But she admitted the first broadcasts last year had also been timely. "It came out at the time of 11 September and was a truly escapist kind of show," she said.

BBC Worldwide was involved from the start in considering how The Blue Planet could be marketed. There was always a danger of oversell, but Mrs Tidmarsh said she did not believe that was a problem in this case. Some of the spin-offs, such as the concerts, have not been attempted before but The Blue Planet lent itself readily to the more adventurous approach.

And international sales of the series itself had been easy because of the programme's universal appeal, Mrs Tidmarsh said. "It was much easier to sell than comedy or drama, which is much more culturally sensitive."