Politics of the United Kingdom
The UK Parliament is the supreme legislative body in the United Kingdom (i.e., there is parliamentary sovereignty), and Government is drawn from and answerable to it. Parliament is bicameral, consisting of the House of Commons and the House of Lords. There is also a devolved Scottish Parliament and devolved Assemblies in Wales and Northern Ireland, with varying degrees of legislative authority.
Separation of powers
A multi-party system parliament that must either form a minority executive or a coalition executive function as a perfectly good system of checks and balances even if it was never a stated goal for the introduction of multiparty system. The multiparty system came about in response to a public outcry of having too few parties and a general feeling of a lack of representation. For this reason you'll find very little on the topic of separation of powers or checks and balances in the works of Norwegian political sciences today.
The development of the British constitution, which is not a codified document, is based on this fusion in the person of the Monarch, who has a formal role to play in the legislature (Parliament, which is where legal and political sovereignty lies, is the Crown-in-Parliament, and is summoned and dissolved by the Sovereign who must give his or her Royal Assent to all Bills so that they become Acts), the executive (the Sovereign appoints all ministers of His/Her Majesty's Government, who govern in the name of the Crown) and the judiciary (the Sovereign, as the fount of justice, appoints all senior judges, and all public prosecutions are brought in his or her name).