Dear Darkafar,
You have posed an interesting question. In my opinion, the Management Representative is the one who commissions the internal audit (client) and he is responsible for the intenral audit process. Hence I would not expect him to carry out an audit on "internal audit". Any internal auditor who has not been involved in establishing/maintaining the procedure for internal audit should be able to audit the internal auditing procedure. Another approach may be to invite an "external" auditor to carry out an audit of the intenral auditing process. This audit being a conformance audit, should ideally confine itself to the assessment of conformance to the established procedure (e.g. audit programme, auditor qualification, audit elements etc.) rather than to assess the quality/content of the internal audit report(s). The latter should be left to be discussed between the Management Representative (client) and the team of internal auditors or the Lead internal auditor.
with best regards,
Ramakrishnan