For my Departments the answer is as follows:
CPS
The DPP, Ken Macdonald QC, is the Accounting Officer. He has an honours degree in politics, philosophy and Economics; and was called to the Bar by the Inner Temple in 1978.
Treasury Solicitor
The Principal Accounting officer for HM Procurator General and Treasury Solicitor is Juliet Wheldon DCB QC. She read history at university and was called to the Bar in 1975.
SFO
The Principal Accounting Officer is the Director of the Serious Fraud Office, Robert Wardle LIB, a solicitor of the Supreme Court who has prosecution experience over 28 years.
RCPO
The Accounting Office of the Revenue and Customs Prosecution Office is David Green QC who is also the Department’s Director. He is a graduate of Cambridge University (MA Hons) and has been a member of the Bar (Inner Temple) since 1979.
The role of the Accounting Officer is one that the Permanent Secretary or Head of Department combines with his/her personal responsibility for the overall organisation, management and staffing of the Department and for Department-wide procedures in financial and other matters. The Accounting Officer is assisted in the discharge of these duties by suitably qualified and experienced senior managers, such as the Finance Director.