Rich families are using "privilege" to disrupt or avoid child abuse investigations, a report has found.
Goldsmiths University found wealthy households were effectively "opting out" of the child protection system.
Social workers had uncovered cases of sexual exploitation and emotional abuse, but found children's services were biased towards poorer families.
Professor Claudia Bernard, who led the study, said neglect cases in affluent areas often went "under the radar".
Prof Bernard told the Local Democracy Reporting Service: "People have these deep-set beliefs that this is happening in poor, dysfunctional families."
Friends in 'high places'
The study received an overwhelming response from social workers who were frustrated by the way they were treated, she said.
All respondents found richer families had a "sense of privilege", subjecting social workers to a level of scrutiny that poorer families did not.
Some participants commented that wealthy parents would only deal with managers, or would belittle social workers with threats of complaints.
One social worker said: "They'll get on to their local councillor, someone who they go hunting or shooting with or play golf with.
"They know people in high places and they threaten you with people as well."
Social workers serving 12 local authorities around the UK were interviewed for the study.
In one case parents of a young girl disclosing sexual abuse complained to the council about the investigation.
Social workers were then rebuffed by school nurses who said there was no way the child's "great mum" would ignore such abuse.
Teenagers in private fee-paying and boarding schools, often isolated from their parents, had complex safeguarding needs, the report found.
Often the issues only came to authorities' attention when parents were dealing with an acrimonious separation and needed a child welfare report, the study said.
The study called for social workers to be trained to deal with affluent families.
The City of London Corporation, which commissioned the report, announced it was adopting the findings into its Service Improvement Plan.
The historic City of London is not strictly a London borough, but special dispensation is given to the corporation to run council services for its 8,000 residents.