The controller of BBC1, Lorraine Heggessey, has commissioned what she terms "the riskiest sitcom" in the channel's history as part of a strategy to make BBC1 "less old-fashioned and fuddy duddy".

The sitcom will star Jasper Carrott and Meera Syal as a mixed-race couple with a child who has cerebral palsy. The child will be played by a child actor, Jamil Dhillon, who has cerebral palsy. The sitcom, which does not yet have a name, will be shown this winter.

Ms Heggessey said the commission was just part of a wider strategy to update the channel. Unpublished BBC research shows that even pensioners think the channel can be "old-fashioned and slightly fuddy-duddy", she said.

She revealed in The Independent when she became controller a year ago that she wanted to end the use of the term "Auntie" for the BBC and change the hot air balloon logo, or "ident". Terry Wogan's show Auntie's Bloomers has already been renamed Bloomers.

Addressing the Broadcasting Press Guild yesterday, Ms Heggessey said: "I still hate the image of Auntie and I will change the idents eventually. We live at a time when people don't call each other by their surnames and they are dressed more informally. We have to reflect that on BBC1."

Ms Heggessey is deemed to have had a successful first year, presiding over improving ratings and a successful transfer of the main evening news to 10pm. "Now," she said, "I am starting to take a few more risks. BBC1 will become a bit more playful and have a bit more attitude."

New commissions include a dramatisation of Arthur Conan Doyle's The Lost World and a live broadcast from the bottom of the ocean.