Ms Mowlam, who is Minister for the Cabinet Office, oversees the Government's code of conduct for ministers. She used the 1994 gift to fund her office when she was shadow secretary of state for national heritage but failed to name Mr Dyke in the Register of Members' Interests even after she was investigated in 1996 for another, similar offence.
The Parliamentary Commissioner for Standards, Elizabeth Filkin, ruled that Ms Mowlam breached the spirit of the registration rules when she declared that she had received the money from the Marjorie Mowlam Research Fund. The Committee on Standards and Privileges decided to take no further action after Ms Mowlam apologised for the oversight.
The donation was one of several Mr Dyke made to Labour before the general election. He is believed to have told the BBC'S board before he was selected that he had paid pounds 55,000, including a donation of pounds 25,000 for the 1997 election campaign, pounds 5,000 for Tony Blair's 1994 leadership campaign and pounds 5,000 each for Ms Mowlam and Jack Cunningham when they were shadow heritage secretaries.
Ms Filkin said she agreed with a ruling by her predecessor, Sir Gordon Downey, who said in 1996 that Ms Mowlam should have registered a pounds 21,000 donation from Mirror Group Newspapers. The Committee on Standards and Privileges added that she should have mentioned her donation from Mr Dyke to Sir Gordon when he investigated the first complaint.
"We are concerned that Dr Mowlam gave inaccurate information to Sir Gordon Downey when he investigated a previous complaint about her. Dr Mowlam told the present commissioner that it had been an oversight on her part," its report said. In the January 1995 register, Ms Mowlam inserted an entry which read: "Researcher paid for partly out of office expenses and partly out of donations to the Marjorie Mowlam Research Fund."
Peter Ainsworth, the shadow Culture Secretary, complained to Ms Filkin after donations by Mr Dyke were revealed during the BBC selection process through which he was chosen to succeed Sir John Birt. A parallel complaint about Mr Cunningham was rejected because he received his gift via a blind trust and did not know the identity of the donor until much later.
Mr Ainsworth said: "I'm prepared to accept that Ms Mowlam's failure to register Greg Dyke's donation was an oversight, although it was a pity she did not take the opportunity to put matters right during the previous Mirror investigation."