It's useful to read this alongside 1.7 of the standard (workforce). A professional, qualified archivist workforce is essential to attain the standard for any substantial service.

But should having a professional archivist be the basis on which you can even think about applying for accreditation? I'm not convinced. There are issues around smaller archives with nonetheless significant collections (e.g. in a learned society with an Hon Archivist able to offer excellent advice, but where the established staff is, say, a librarian). I'd be concerned if such an archive were excluded from accreditation full stop, though they would certainly need to demonstrate the robustness of their arrangements in order to meet the standard.

I don't think it needs to be on the staff, but that they should have access to professional advice before being able to apply for recognition by the leader of the archives sector seems just basic to me.

I agree with the need for access to professional staff. Just to add that the access should be conservation skills as well as archival

Museum accreditation addresses this with mentors, though I'm not sure the relationship is always very close. There needs to be more than potential access to professional advice - it needs to be accessed and used.

Is this something that should vary with the size of the collections and/or of the institution that holds them?

If the criteria specified that archives smaller than X (?and archives that are part of institutions with no or very few paid staff) need regular access to appropriate professional advice, but larger archives need to have staff with relevant qualifications and/or experience, would that be fair and reasonable? I'd like to see something along these lines in the criteria, but I suppose the dividing line would be contentious and it could prove unworkable.