How does devolution challenge parliamentary sovereignty?

Devolution challenges parliamentary sovereignty in three key ways: 1) The cases of where legislation is put in place and it conflicts with that of the devolved body. For example: in Scotland there are no tuition fees to be paid for local students at higher education (universities). However, in England, tuition fees are applicable. The national narrative at the moment is to debate the continued existence of this fee structure. Here, we have the practice of devolution challenging Parliamentary sovereignty because it creates a different narrative to what is dominant in the government's agenda. 2) Devolution often leads to the devolved bodies asking for more powers, if you compare and contrast the powers that Scotland, Wales and Northern Ireland have they all differ to varying degrees, all regions however have nationalist representatives seeking independence from Westminster politically. 3) Finally, parliamentary sovereignty as it stands, whilst the UK remains in the EU means that the UK sovereignty is being brought into question, this adds various layers of complexity to working out where sovereignty lies and who the key decision maker is.