Richard and Judy's new boss warns them to sharpen their act or expect the chop

Richard and Judy, the king and queen of daytime television who were poached last year for an estimated £2m by Channel 4, will have to improve their performance if their new programme is to avoid the axe, the broadcaster warned yesterday.

Tim Gardam, Channel 4's director of programming, said the husband-and-wife team's show, broadcast at 5pm on weekdays, had to "get better" and become "more consistent". Richard and Judy has been without an editor since the recent and unexplained departure of Karen Smith.

Mr Gardam, whose comments provoked speculation that their contract could be scrapped after its first year, said the final 15 minutes of the hour-long show proved particularly problematic. With average viewing figures of about 2 million dropping further at 5.45pm, the producers needed to find a way of keeping the audience at that level, he said.

But he added: "Programmes like this don't launch fully formed. They don't go right from day one, they take time to develop."

He denied Channel 4 was considering moving the show from 5pm to an earlier afternoon slot because of the low ratings. Doing so would require moving the successful shows, Fifteen to One and Countdown, which would be damaging. "That's the bulwark of our afternoon schedule and we'd be breaking it apart," he said.

After a 13-year spell at ITV, Richard Madeley and Judy Finnigan were hired last summer in a move designed to build on the popularity of Countdown to bolster Channel 4's teatime schedules.

But critics were astounded at the signing, which seemed entirely contrary to the spirit of Channel 4's remit.

Mr Gardam said the show had improved since it started. "When it gets stories that chime with the audience it does very well indeed," he said.

The future of Richard and Judy was raised at the launch of Channel 4's spring and summer schedule, which was notable for a line-up of programmes likely to rattle the Establishment.

Mo Mowlam, the former secretary of state for Northern Ireland, is expected to blow the lid off the inner workings of Tony Blair's Government in a programme explaining how she went from being Parliament's darling to a life of political obscurity. She said: "I want to be honest about why I left because otherwise it's difficult to understand."

Mr Gardam said the Government might be uncomfortable because Ms Mowlam was by far the most important former cabinet member to speak out. "The Government is easily embarrassed. And the point about Mo Mowlam is she has an absolute reputation with the public for telling the truth."

Another programme will put the spotlight on the Prime Minister as he reaches his fifth anniversary in power, while the Queen's golden jubilee will be marked with a tribute from the caustic impressionist Rory Bremner and a special investigation into the royal finances.

A programme by the film maker Molly Dineen profiles the dying days of the old House of Lords.

The channel is to broadcast a third series of Big Brother although Mr Gardam promised there would be a new twist to the rules.

The channel's tradition of snapping up some of the best American drama will be maintained with the signing of Six Feet Under. Scripted by Alan Ball, the Oscar-winning writer of the film American Beauty, Mr Gardam predicted it would be as big as The Sopranos.

And in a schedule surprisingly devoid of Channel 4's usual quotient of sex, an exception will be a show featuring animals that display homosexual behaviour.

A BBC executive was accused yesterday in the House of Commons of writing an "offensive" letter to a senior MP. Gerald Kaufman, chairman of the Culture Select Committee, accused Michael Hastings of "impertinence" after he wrote to Mr Kaufman saying MPs were focusing too much on the BBC in a new communications Bill.