(UK) Public Interest Immunity?

This morning I received yet another lengthy letter from my adoption agency's legal representatives to my lawyer. On the whole yet another glorified backside covering exercise. It mentions as one of its excuses for continuing to withhold access to various records and correspondence about what was a very dodgy adoption, a 'Public Interest Immunity where matters of the adoption of a child are concerned'. From what I remember of reading the transcripts of the Gunn-Rosso judgement, an agency might claim immunity from laws requiring disclosure in other circumstances because it might undermine the public's confidence in adoption. The agency's solicitor says '....Barnardos have an additional duty to ensure in their capacity as holders of adoption information and having involved in an adoption process, the public interest in disclosing the material is such that it should be disclosed. This is an overriding duty placed by law on Barnardos and one which they take very seriously...' I suspected it could be disputed that it is an "overriding duty" particularly as Barnardos has always in the past steadfastly maintained that its "overriding duty" was one of care to those involved. Strange then, that when it become possible to prove that those who they were previously exercising a duty of care towards, have deceased, then that duty of care becomes no longer the "overriding" duty, giving way to public interest duty which in its view now overrides its duty of care to me or presumably any other of its former inmates in my position. Has anyone else here been given 'Public Interest Immunity' as a reason for withholding access to records of an adoption, or of fostering or time in care particularly where care and fostering records have been annexed (probably illegally) to an adoption record in order to deem them un-discloseable? Robin