Salus Populi Suprema Lex

There cannot be a Supreme Court in a sovereign parliamentary democracy.

How would the Attlee Government have fared against a Supreme Court?

If there must be a body by that name, then all appointments to it, and all rulings of it, must be subject to confirmatory resolution of the House of Commons, the High Court of Parliament.

Yes, that does necessitate primaries at least for major party candidates.

And yes, it does necessitate an element of Proportional Representation.

But above all, it necessitates far greater economic equality, without which universal suffrage is effectively meaningless, as is equal liberty under the law.

If some people are far richer than others, then their votes and their liberties must inevitably count far more than the votes and liberties of others.