The watchdog said services had improved since November 2010 when 2, 700 vulnerable children were without a social worker.

BBC: Kent's children's services rated 'adequate' by Ofsted

In another move to strengthen social work the government has announced that Isabelle Trowler who reformed children's services in the London Borough of Hackney, has been appointed England's first Chief Social Worker.

BBC: Social work scheme will fast-track top graduates

The survey of social services departments in England by 78 authorities found that there was a 14.7% vacancy rate of social worker posts in July.

BBC: mother and child