In the last few months, the UK has seen what might be called an "activist parliament". There have been comments on TV/radio in the context of Brexit, that MPs have been setting their own agenda, not just following voting days set by government, and so on.
I understand that the UK model is that Parliament has absolute legal authority, and the govt chooses the agenda to allow them to follow their legislative/platform agenda.
But my understanding of the "modern traditional norms" is pretty hazy - the varied and unwritten understandings that have habitually delineated the Government and Parliament's respective spheres, areas of authority over national matters, demarcations, prerogatives, and conventions. (For example, the recent resignation of a minister because traditionally a member of the government can't/shouldn't move to modify a government matter, suggests two distinct "sides")
I expect these understandings/norms have changed over time, and that Brexit is completely atypical and in a category of its own (but may be changing those norms).
What are the traditional understandings in these areas, within say, the last 50 years (or the post-WW2 era if a better choice of time period) and how have they gradually changed/how are they changing nowadays?
I'm somewhat interested in what's driving it, but mainly for this, I'm mostly interested in focusing on how it is, and how its changing/changed/evolving/evolved.