Freedom of Religion: Does the Queen's position as head of Church of England interfere with separation of state and church?

It doesn't interfere with the separation of church and state for three reasons:   Firstly, as others point out, that's an American ideal which does not apply in Britain.  The United Kingdom is technically a theocracy with a church leader as its head of state.  There is no separation of church and state with which to interfere.   Secondly, the Queen has effectively no actual power in the administration of government.  She cannot over-rule parliament, she cannot declare war, sign treaties, set budgets, etc., etc.   Lastly, we British are much too laid back to worry about that sort of thing anyway.  Britain is, despite being a theocracy, not a very religious country.  As this graph in the link below shows, the number of people actually attending church (as opposed to just saying Christian on the census form) is steadily declining, and the number of active Anglicans was under 1 million by 2005.  The UK has a population around 60 million.  Put in perspective, that's less than voted for the Green Party in the last election.   http://www.brin.ac.uk/news/2011/church-attendance-in-england-1980-2005/

TVtropes calls this "Eagleland Osmosis". American media and culture are so influential that people start thinking that legal concepts exclusive to America are somehow universal, including things like the Miranda warning, freedom of speech and the separation of church and state. It's not uncommon for western nations to have some version of these rules, but they aren't global law.   The concept of separation of church and state was a fairly new concept when it was implemented in the United States. While many wealthy countries have far less religion in the public square than does the US, separation of church and state is by no means an official rule.

No, it is precisely because of the CofE's position as the established religion with the Queen as Head of the Church that there is a de facto separation of church and state. Very unlike the USA. Each arm or estate of the State swears allegiance to the Queen who, as a constitutional monarch has very few executive powers, except for embodying the separation of powers. The reason for this somewhat quaint position is that in the past Roman Catholics (and others) have sworn allegiance to the Pope with the specific intention of destroying democracy in the UK and supplanting it with an absolute monarch little more than a puppet of the Pope.   Ever since James II the separation of Church and State has been absolute and it is one of the reasons why the monarchy exists, to embody this separation. In the same way MPs swear allegiance to the Queen, who is forbidden to enter the House of Commons and their separation is also maintained.   Interestingly, the old oath of Allegiance made by MPs under Queen Victoria contained no reference to religion or God at all, and the reference to "So help me God" is an optional extra even today. (AS an aside, many people in the UK decline to take the oath in court on a Bible. This is fairly normal. I was told (I don't know how true this is) by a US visitor that taking the oath without the Bible in the US might get you slung out in some States.). One of the reasons why Edward VIII had to go was his absurd, almost comical, ideas on the role of the monarch   So representatives of the Lords Spiritual sit in the House of Lords and help in the work of the  work of the Lords in reviewing proposed legislation. All of them have sworn the oath of allegiance to the Queen   If you look at the US oath of allegiance they swear to uphold the Constitution as though it were more than simply a text. In that regard our Monarchy and the American Consitution perform something of  the same task.

The queen's titular position as head of the Church of England does not affect the relationship of church and state, but it does compromise her. Her actual political position is no different than her presidency of many British associations, and as she would no doubt say the real head of the church is Jesus Christ. The problem with the Church being by law appointed is that in fact it is controlled by politicians, many of dubious christian credentials, who recommend bishops and archbishops. These bishops themselves are politically active in the House of Lords. It would probably be better and lead to a refreshing of British Christianity if both the English and Scottish churches were disestablished. The monarch could then just be titular president and as a genuine believer that would not be a problem with the present queen.

Yes.  But separation of church and state is much more an American concept than a British one.  Britain still has freedom of religion, although the Queen is the de jure head of the Church, and of the Nation, she has very little power, and less authority, in either.A more interesting problem though is that violates human rights.  The monarch is forbidden from marrying a Catholic.   This isn't an issue in this generation, as William has found himself a nice Anglican wife, but it still sounds like an imposition on their human rights.  While it's probably not illegal, it would be a strange situation if they were to convert, to, for example, Islam - could the spiritual head of the Church of England be a Muslim?  It's also, I think, a restriction on their human rights that they're not allowed to be involved in politics.

Believe it or not, the first amendment to the United States Constitution does not apply in England. Our separation of church and state does not extend across the pond, nor does it need to. Apparently they are able to manage quite nicely without the benefit of constitutional imperatives.