https://www.parliament.uk/about/how/role/sovereignty/
'Parliamentary sovereignty is a principle of the UK constitution. It makes Parliament the supreme legal authority in the UK, which can create or end any law. Generally, the courts cannot overrule its legislation and no Parliament can pass laws that future Parliaments cannot change. Parliamentary sovereignty is the most important part of the UK constitution.'
...
'Over the years, Parliament has passed laws that limit the application of parliamentary sovereignty. These laws reflect political developments both within and outside the UK.
They include:
- The devolution of power to bodies like the Scottish Parliament and Senedd Cymru.
- The Human Rights Act 1998.
- The UK's entry to the European Union in 1973 - and subsequent exit in 2020.
- The decision to establish a UK Supreme Court in 2009, which ends the House of Lords function as the UK's final court of appeal.
These developments do not fundamentally undermine the principle of parliamentary sovereignty, since, in theory at least, Parliament could repeal any of the laws implementing these changes..'