Cameron is successful because he has surrounded himself with people he can trust and depend on. These are the tried and tested methods that any successful leader will use. Both Thatcher and Blair had small teams they depended on as did Harold Wilson before them. All were successful leaders.
(Note: I don't agree with pretty much anything Bliar did, but he was successful at being a leader.)
The only problem with this is that politicians are, pretty much to a cunt, self-important, overweening, jumped-up, cock-sniffing arse-biscuits who feel that everybody, including the Alpha Male, has to listen to their words of wisdom. So in politics, eventually this perfectly sound and effective policy will lead to briefings, whispers, rebellion and an increase in "inclusion". And then, as we saw with Blair most recently, it all goes to hell in a handbasket.
Politicians, eh? Loathe them or kill them, you can't do anything useful with them.