CISRS document CAP 609 is fairly clear but because there are now separate basic and advanced inspection cards available which changes things a bit, the casual Health & Safety person probably hasn't bothered to look up chapter and verse. It may be worth pointing him at the CAP609 extract which follows:
The stance of both the NASC and CISRS is that CISRS Scaffolders and Advanced
card holders are competent to inspect scaffold structures up to the grade of the
card they hold, provided their employer can demonstrate they have the necessary
knowledge and experience. This will remain for the foreseeable future. CISRS
Scaffolder Part 2 and Advanced courses being introduced in 2016/17 will include
formal elements of Scaffold Inspection. CISRS cards that are issued subsequent
to these courses will be endorsed with this training. Accordingly CISRS Scaffolder
cards will be endorsed with Basic SITS and CISRS Advanced Scaffolder Cards will
be endorsed with Advanced SITS. Scaffolders holding an endorsed card will not be
required to hold a separate Inspection Card.