Divine Authority and why the Church is the State

Authority to rule has long been understood as ordained from God. Although the Church of England is the only national Church in the world, the notion that the Monarch as God is actually a well-established diplomatic convention, particularly as relates to matters regarding the Head of State.
In the Church of England, the Monarch is the 'Supreme Governor', and the Archbishop of Canterbury is the Spiritual Head of the Church. Within the second chamber of the House of Lords - forming the upper house of the legislature - other Bishops from the Church of England, also serve - but interestingly, not the Archbishop of Jerusalem, why is that?
Regardless of whether the Archbishop of Jerusalem is a Palestinian Christian, and therefore from the line of David, surely the position itself - regardless of linage -should at least match the spiritual authority of the Archbishop of Canterbury?
Although he was the first Palestinian Anglican Bishop of Jerusalem, my grandfather Bishop Haddad did not sit in the House of Lords in London within the Church of England - he sat in the heart of Christendom, in Jerusalem.
Now it seems to me that this matter is of great historic and diplomatic importance, particularly now that the Sovereignty of the State of Palestine is being so seriously discussed. There are some who say that you cannot have a Sovereignty in Palestine without ending the Israeli occupation, and yet others who say that there can be no Sovereign State without a Sovereign Church of Palestine.
As for me, I continue to pray to Christ, our King, for spiritual guidance, and wisdom, that our God may reveal himself to all our leaders, whether they sit in Church, or State.