ISA 300 Planning an audit of financial statements requires the auditor to plan his audit work so that the audit will be performed in an effective manner. 

Required: 

a) Explain why the need for planning exists and what benefits are to be derived from adopting such an approach.

b) Set out the steps you would take prior to the commencement of an audit of a limited company which has been a client for a number of years.

c) Planning is equally relevant to the work of the internal auditor. Explain how the internal auditor's planning differs to that of the external auditor.