Thank goodness for the monarchy. Otherwise any damned Prime Minister might otherwise be corrupt. But they daren't. All the important institutions swear allegiance to the crown, not the party in power.
The US is missing a key piece of a trust framework. It needs a non-political person or body keeping an eye on the separate branches in order to ensure they uphold their oaths to protect the constitution.
The Supreme Court performed that role to some extent until it became partisan. But the GOP targetting of that body has tarnished it. The non-partisan piece of a constitution is its key element. It's the difference between a democracy and a banana republic.