Excellent points. In practice, however, much of a country’s governance resides on tradition, not the letter of it’s constitution. For example, whereas our prime minister appoints senior judges, our judicial branch has a long history of independence from government. It can be very different in other countries, where appointed judges will rarely if ever defy the executive.

The British system of parliament has evolved over hundreds of years, and much of it isn’t codified in constitutional law. That might seem dangerous, but in practice it’s not. No matter what’s written in a constitution, it can always be changed or amended. Practice and tradition are just as strong, or stronger even, than mere words on paper.