Following my two previous posts, just a thought. Why doesn't some-one (e.g. Ofsted, the Department for Education, the LGA) collect some basic data about recruitment and retention of children's social workers - and publish it?
The Local Government Workforce Survey - published by the LGA - doesn't really provide the kind of detail required. I'd suggest the following: vacancy rate, turnover, average time in post of current staff, reasons for leaving, proportion of agency workers, proportion of newly qualified staff in post, proportion of staff recruited abroad. All of that must be available in the HR systems of local authorities and could easily be sent to a central point for collation.
Having that sort of data would not only give a clear national picture, but would allow the identification of areas where the problems were most severe.