I'm sorry, but I've had to remove the question as a major component of it is asking about the current situation in, presumably, the United Kingdom. Feel free to ask again just with the latter part, asking how the role evolved through the mid-20th century though, but just make sure that you aren't asking about post-1994!

I would also recommend clarifying two things when you do. Firstly, which Queen you mean, and second whether you mean the role of a Queen through time (Queen regent has a vastly different role than Queen consort), the role specifically of Queen regents, or the role of the Monarch, regardless of gender, as you will get vastly different answers for each one.