Tests of control

No. Enquiry is not necessarily a test of control either as you might simply be asking if they split out VAT on purchases. That tests no control. Written representation is substantive evidence.

However, there are scenarios I've seen where enquiry could be a reliable test of control, for example, Enquiring of the finance director as to how changes to the masterfile are being performed.

I said that enquiry is not necessarily a test of control. For example: 1 Do you approve invoices? This is a test of control, though weak, as it is addressimg a control function, the checking. 2 Are there any liabilities that have not been recognised in the FS? This is not a ToC. No controls are being checked. It is a weak substantive test.