Lord Laming told the education select committee this week that it was "pretty drastic" that Ealing social services department had grown worse.
The peer was the first witness to give evidence to an investigation by MPs into the Government's Every Child Matters paper, which responded to the Climbie inquiry.
The paper led to the recently-passed Children Act, which aims to improve child protection by getting all public services that deal with children to co-operate more closely.
Lord Laming said he had been pleased with the way the Government had responded to his recommendations through the Act and by creating the post of a children's minister.
But he said he was disappointed that the work of local social services'
departments remained "a mixed picture".
Ealing council, in west London, was one of only eight in England to receive a zero star rating for its social services work in a table published last week by the Commission for Social Care Inspection.
The authority, which came into contact with Victoria on her second day in England, was also one of only two which saw the quality of its social services decline since its last inspection.
The select committee also heard from Phil Collins, director of the Social Market Foundation. He said that the main stumbling-block for the Government's plans would be professional rivalries between staff such as teachers and social workers.
"The tensions between people who see themselves as educators and people who see themselves as carers are already looming," Mr Collins said.
A spokeswoman for Ealing council said the no-star rating for its social services department was mainly related to its work with adults and that inspectors had found it served most children well.