After critically analyzing and evaluating above facts we can identify what is the essence of the British constitution. Is it the unwritten nature of the British Constitution? Or whose dominant characteristic is the sovereignty of Parliament?
The term Constitution is defined in many ways by various professors, philosophers and Constitutional scholars. It basically means set of rules to govern citizens within a state. Finer has defined Constitution as:
“Codes of rules which aspire to regulate the allocation of functions, powers and duties among the various agencies and officers of government, and define the relationships between them and the public." 
In some countries those code of rules are written and in some countries they are unwritten. Constitutional document is the superior law to all other laws in the state. The United Kingdom Constitution is unwritten, Parliamentary, flexible, monarchical and quasi-federal.
Thus it is said that Constitution is unwritten, it is written in several of the principal sources. It is not exist in documentary form, it is UN codified. Acts of Parliament and common law which have been established by the courts are written sources of UK Parliament.
The Constitution must amend according to the current society needs. To make amendments in documentary Constitutions it takes special procedures. Whole of part 5(art 38-49) of Canadian Constitution (1982) is given according to the amending the Constitution. In Indian Constitution Article 368(2) prove about the special procedure to amend the Constitution.
“An amendment of this Constitution may be initiated only by the introduction of a bill for the purpose in either House of Parliament, and when the Bill is passed in each House by a majority of the total membership of that House and by a majority of not less than two-thirds of the members of that House present and voting……" 
But in UK Constitution it is simple to amend by passing an Act of Parliament because the Constitution is unwritten. So UK Constitution is flexible. But it is because of the Parliamentary sovereignty to pass an act to amend the Constitution.
Because there’s no written Constitution to protect civil liberties Magna Carta was drafted by Archbishop Langton and the most powerful Barons of England in 1215. Magna Carta was forced to signing by English King John because it reduce the power of the King and allowed the formation of a Parliament. It is the beginning of the UK Parliament and English citizen’s rights.
In end of 17th century the current king James II was forced to leave the country and was replaced by his daughter Mary and her husband William on the condition that two would accept declaration of rights in exchange of the throne. The declaration was known as the Bill of Rights in 1689. In this declaration the king (Monarch) cannot suspend a law voted in Parliament and the king cannot raise taxes or maintain a permanent army in time of peace without a vote in Parliament. This is called the “Glorious Revolution" where the Parliament became supreme.
Because of “Glorious Revolution" Parliament became more powerful then Monarch. British king/queen was said to reign but not to rule. Later on, the cabinet government and the prime Minister progressively emerged and it became the ultimate rights of the British people. Because ministers are chosen from British citizens vote.
Only the Acts of Parliament are supreme because to become an Act of the Parliament there is a long process. It is starting from a bill to become an Act. And the Bill must be approved by Royal Assent as well. Because of the “Glorious Revolution" queen must approve the Bill as a convention. The courts cannot interfere with the internal proceedings of the parliament. According to the ‘enrolled Act rule’ courts can only apply the law. A resolution of the House of Commons will not be enforced by the courts. For an example, Bowles v Bank of England  .
Lord Campbell has mentioned in 1842:
“All that the Court of Justice can do is to look to the Parliament roll: if from that it should appear that a Bill has passed both Houses and received the royal Assent, no Court of Justice can inquire into the mode in which it was introduced into Parliament , or into what was done previous to its introduction, or what passed in Parliament during its progress in its various stages through both Houses." 
As mention in Lord Campbell, courts cannot look how the Act came into being and only can check whether Act is valid or not. For an example Edinburgh and Dalkeith v Wauchope  and confirmed in Picken v BRB 
The supreme point in Parliamentary Sovereignty is that Parliament can legislate on any matter. Even has power to legalise past illegalities and alter the law retrospectively .Retrospective legislations has passed to protect illegal Act committed in the national interest.
“On upon the faith of the then existing law . . . Accordingly the court will not ascribe retrospective force to new laws affecting rights unless by express words or necessary implication it appears that such was the intention of the legislature." 
For an example Burmah Oil Co (Burma Trading) Ltd v Lord Advocate  where the courts awarded damages to the Burmah Oil and Parliament responded with the War Damage Act (1965), which acted on this case retrospectively to reverse the decision.
Parliament acts 1911 and 1949 has improved powers of House of Commons( which can be called as people’s democratic Parliament). Because of parliament Act 1911 and 1949 House of Commons can pass an Act without the approval of House of Lords. It arose because of 1909 Finance Bill was not passed by House of Lords. Using Parliament Act 1911 and 1949 House of Commons have passed several important Acts such as War Crimes Act 1991(which mentioned above), Government of Ireland Act 1914, the European Parliamentary Election Act 1999, the Sexual Offence Act 2000, and the Hunting Act 2004.
In the case Jackson and others v Attorney General  , J and others challenge the Hunting Act is invalid because it was made under authority of the Parliament Act 1949 which, they considered it is also invalid. But the DC held that:
“The 1949 Act was a valid Act and that the 2004 Act was also therefore valid. In its judgment, the Parliament Acts procedure could be used to make any laws, save for the expressly excluded by s 2(1) of the 1911 Act." 
The Parliament Act 1911 and 1949 has made the Parliament more dominant in UK Constitution in passing Acts and it conclude the power of sovereignty of Parliament.
In 1885 Professor Albert Venn Dicey has mention in his book ‘The Law of the Constitution’, that British Constitution rest upon two principles such as legal sovereignty of Parliament and the other one is Rule of law because British has a unwritten Constitution. The rule of law stands against government abusing powers. But rule of law is not permit to stand in the way of parliament’s Acts. Dicey summarized his views as:
“The Principle of Parliamentary sovereignty means neither more nor less than this namely, that Parliament has, under the English Constitution, the right to make or unmake any law whatever: and, further, that no person or body is recognized by the law as having a right to override or set aside the legislation of Parliament" 
The rule of law helps Acts of the Parliament to apply them in courts. British unwritten constitution, rest upon rule of law and the sovereignty of Parliament. But rule of law; rest upon sovereignty of parliament as mention below.
“In our society the rule of law rest upon twin foundations: the sovereignty of the queen in Parliament in making the law and the sovereignty of the queen’s courts in interpreting and applying the law" 
It conclude rule of law what is a principle of UK unwritten constitution even depend on Parliament sovereignty.
The Sovereignty of Parliament is more expressed in term ‘doctrine of implied repeal’. That means Parliament is unable to bind its successors. If a later Act conflict with an earlier Act, Parliament will remove the former Act by express repeal. For an example, Vauxhall Estates Ltd v Liverpool Corpn  and Ellen Estates Ltd v Minister of Health  . Where the Maugham LJ stated:
“The legislature cannot, according to our constitution, bind itself as to the form of subsequent legislation, and it is impossible for Parliament to enact that in a subsequent statute dealing with the same subject matter there can be no implied repeal. If in a subsequent Act Parliament chooses to make it plan that the earlier statute is being to some extent repealed, effect must be given to that intention just because it is the will of the legislature" 
There are facts limiting the sovereignty of UK Parliament. One of the facts is Devolution to Scottish Parliament. Because of the Scottish Act 1998 Scottish Parliament can pass own Acts without the concern of UK Parliament. And it has reduced the legislation power over the Scotland in UK Parliament. But still under the unwritten Constitution UK Parliament can express repeal or amended the Scotland Act 1998. If they do so it will be a breach of a Convention. But anyway it is because of the UK Parliamentary Sovereignty that Scottish Act can be express repeal.
As well as Scottish Act, Human Rights Act is not given entrench rights. Human Rights act can be repealed in any time, by majority votes from House of Commons. Even it is weaker than ordinary Act in Parliament, because it does not automatically override inconsistent pre-existing acts. Courts are not allowed to invalidate Acts of Parliament which are incompatible with Human Rights Act 1998.
UK Constitution is changing towards having an UN-codified Constitution to codified Constitution. It is because of the treaties Britain having with other states and Organizations. Main sources in UK Constitution are written as Statutes, Common law, Bill of Rights and treaties.
Because the UK Parliament is Sovereign it can amend the Constitution at any stage. It is the will of citizens, because citizens have elected the members of the Parliament. Legislator has the power to domain the UK Constitution. With the effect of doctrine of implied repeal, retrospective legislation and rule of law Parliament domain the UK Constitution.
Even in conflicts in international law, because of UK Parliament is Sovereign domestic law is supreme (Mortensen v Peters  ). If Parliament is not sovereign Britain Constitution will collapse. Therefore I may conclude that the essence of the Britain Constitution is dominant characteristic is the Sovereignty of Parliament.