this is what i have so far? Sovereignty means ultimate political authority. Parliamentary sovereignty is said to be the key element of British constitution. Legally this means that parliament has absolute control and unlimited authority and is the supreme law making body in Grate Britain.
The dilution of authority caused by the impact of, for example, European legislation, as Dave mentioned, is very important. The fact that we are members though is an interesting point for consideration.
Right of appeal to courts outside of our jurisdiction too eg the ECHR and human rights impact. Examples would be illustrative.