I'll start a fight here....
No, bandit, thats not your style...
First off: on the whole I think British actors are much more well-rounded and skillful than American actors, mainly because they are required to learn stage work and Shakespeare. American actors, it seems, just have to be pretty and they can manage to get a job. There are some outstanding American actors out there, but they are becoming the exception to the rule.
Yes, the high quality of British actors is part of what makes so many British TV shows so good. And probably stage work and Shakespeare are keeping the quality high.
What I do feel is inequitable is that Hollywood is openly Anglophile, and has been for many years. British and Aussie actors are highly valued in Hollywood and on Broadway and get many of the cream roles. However, such is not the case in England, where American actors, (even those who are graduates from RADA or Central) are shunned by British agents, theaters and television. I have read where American ex-pat actors in England are not recruited by agents there because those agencies assume that no West End theater or TV company will hire an American, regardless of talent or skills. There is a surplus of Britiush actors already waiting, so they don't even try to push American actors for roles. .
I can't really comment on this, but as an Aussie I see a similar problem. Actors here often complain about the number of American actors brought over to headline big Aussie movies. Their names are needed to sell the movie in America. Yes many Aussie actors go to Hollywood, but here they say it is because they can't easily get lead roles in big movies here.
They used to dream of going back to the mother country and appearing on the London stage or in a British TV show. Now their dream is a role in an American movie.
Gillian Anderson (X-Files) is the only American-born actress in London who regularly gets parts in British TV or theater, but that is only because she was raised in England and has dual citizenship.
There seems to be a "take care of our own" mentality in England that systematically excludes actors from countries outside the Commonwealth.
Am I wrong?
Yes you are wrong I think, but on a technicality. I don't think the boundary is the Commonwealth, it is UK or perhaps Europe.
Part of me thinks that is a good thing. Us Aussies would probably lower the standard of British shows.
Or is that my cultural cringe showing? I can't imagine a similar thread on Aussie TV shows, it would be too short and boring.