Thirty-two years after writing South East Asia on a Shoestring, Tony and Maureen Wheeler sold a controlling interest in the publisher Lonely Planet to the BBC yesterday, netting them about £40 million.

The sale comes after months of negotiations with the broadcaster but will not necessarily see Lonely Planet programmes appear alongside Coast or Michael Palin’s travelogues on BBC television in Britain.

The acquisition is part of the BBC’s plan to expand its commercial arm, Worldwide, into important markets around the world, while the Wheelers get the chance to move into semi-retirement after building a business worth nearly £100 million.

The deal also courted controversy, with one influential MP asking whether the BBC should own a company with little connection to the broadcaster.

John Whittingdale, the Conservative chairman of the Culture, Media and Sport Select Committee, asked: “Why should the BBC effectively nationalise a publisher? Where do its commercial activities stop?”

Mr Wheeler, a Briton who travelled to Melbourne and settled with his wife, Maureen, said that it was time to sell because “we’re getting old”. There was also a recognition that they needed a larger partner to help to manage the transition to digital.

“All media are in transition, and while guidebooks are not in decline, their growth is not as strong as they have been in the past,” he said. The couple had rejected many approaches, saying that they were looking for a long-term, stable home.

“We didn’t want to sell to somebody who would simply sell it on to somebody else, or to one of our competitors,” Mr Wheeler said.

It was not until the BBC was introduced to them in March, at a time when they were considering getting out, that secret talks leading to a sale began. No auction took place.

The Wheelers will cut their 70 per shareholding to 25 per cent, while John Singleton, a sleeping partner, is selling his 30 per cent. BBC Worldwide is tapping its £350 million overdraft to fund the deal.

Lonely Planet sells about seven million books a year, worth about A$120 million (£50 million), having single-handedly invented the genre of the independent travel guide.

Although it is profitable, the precise level of income was not revealed. However, a well-run book business should be able to generate returns of about 8 to 10 per cent.

BBC Worldwide plans to help Lonely Planet to develop its website, launch magazines in the UK, Australia and the United States and develop its modest television production business.

John Smith, BBC Worldwide’s chief executive, said fair trading rules meant that the commercial arm could not insist that Lonely Planet programming is aired on BBC UK channels.

“It will be up to the BBC at home to choose what to do – you’ll probably see Lonely Planet on our commercial channels like UK TV,” he said.

The commercial operation is semi-independent of the licence-fee funded part of the BBC. Last year it made £111 million operating profit on sales of £810 million.

It is responsible for the BBC’s international activities, plus some paid-for products including Radio Times and half of UK TV in Britain.

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