OK, I read the link provided by Nick above and it says:
"The entire series has been closed: since the collection was accessioned in 2014 it is is not catalogued by name of individual as many may still be alive – we believe that the youngest of them was born in 1928. The collection can contain sensitive information about living individuals so, with the support of volunteers, we have started to catalogue the entire series: this enables us to open records for those born more than 100 years ago or where we have proof of death. This ambitious project will continue until the end of 2020 and for the main we are working our way through the series alphabetically by surname.
This page, under ‘Arrangement’, provides a link to the projected completion stages of the project, subject to change. Fifteen per cent of the collection has now been catalogued by name of individual; we have loaded this information on Discovery so researchers can access the material on site or arrange for digital or paper copies to be sent to them. We are offering a paid search service for uncatalogued pieces for those who do not want to wait until the project has completed: details of this service are available at piece level descriptions in Discovery."
So it is a work in progress, and some files are to be closed according to the British law, it will remain a work in progress up to 2028 maybe.