The provision's fairly straightforward. What it does is it provides an authority for the Prime Minister to identify persons who have had the task of providing support and advice during the time after an election, the so-called transition period leading up to the swearing in of the Prime Minister. In essence, it allows the Prime Minister to identify those people who have been acting in that capacity as being within the definition of “senior public office holders”, to whom the five-year ban on lobbying will apply.
On June 12th, 2006. See this statement in context.