Statutory responsibilities
This brings me back to the present time. In most countries where auditing has developed beyond the rudiments, it is an implicit or explicit rule that the auditor bears some responsibility for the existence of an adequate internal control system. I understand that the British Companies Act explicitly requires the auditors to state that proper books of account have been kept. In my opinion, that implies that an adequate system of internal control exists.
Ignoring the computer for auditing purposes (auditing around the computer), the auditor thus has to satisfy himself on that system. He cannot leave out a survey of internal control just because the computer seems so difficult to handle.