19.—(1) An appropriate authority which is carrying out an investigation on its own behalf may—
(a)combine that investigation with another such investigation; or
(b)split that investigation into two or more such separate investigations
if it considers that it is more efficient and effective, or is otherwise in the public interest, to do so.
(2) Subject to paragraph (3), where the Commission is supervising, managing or carrying out an investigation, it may—
(a)combine that investigation with another investigation; or
(b)split that investigation into two or more separate investigations,
if it considers that it is more efficient and effective, or is otherwise in the public interest, to do so.
(3) The Commission shall not take any action under paragraph (2) in relation to a supervised or managed investigation except after consultation with the appropriate authority.
(4) Nothing in this regulation shall prevent the Commission from determining that—
(a)where an investigation is split into two or more separate investigations, those investigations may take different forms;
(b)two or more separate investigations which take different forms (including an investigation being carried out by the appropriate authority on its own behalf) may be combined into a single investigation.