Thanks for that comment, Richard.   In some ways the system I suggested is not that different to the US system, where some Presidential appointments have to be confirmed by the Senate (?); I assumed that the appointments would be effective on an acting basis where necessary before the formal confirmation, but I accept this could lead to the parties allowing long delays between acting appointment and confirmation, so it would need some mechanism to prevent that.

My main objections to my own idea are twofold: (a) how do we ensure anyone is ever confirmed, because almost by definition the majority of the population does not want that party in power and (b) how could we stop the media having undue influence on the selection panel.