Finding a suitable replacement for Ms Ball, an instrumental figure in the revival of fortunes of the station, could prove to be a difficult proposition for the Corporation.
She arrested the decline of the breakfast show's audience following the departure of Chris Evans to Virgin Radio and has in recent months built up the audience figures again. In the last Rajar radio audience figures, released in July, the number of listeners to the show had increased by 200,000 in three months to an average of 6.9 million each week. Ms Ball joined the station in October 1997 to replace Mark Radcliffe, who had unsuccessfully filled the slot after Mr Evans' departure. Last month she married the dance music star and DJ, Norman Cook, also known as Fatboy Slim. Ms Ball said yesterday: "I'm looking forward to extra time with Norman and planning a family. I'm taking a complete career break."
A spokesman for Radio 1 said that he was confident that Ms Ball would return to the station. But her departure is open-ended and Radio 1 has the problem of finding someone who is able to maintain her ratings yet willing to stand down if she should return.