Indeed you're correct, and even orbiter dicta in the Supreme Court (nee House of Lords Appellate Committee) has suggested that Parliamentary Sovereignty is not

Indeed you're correct, and even orbiter dicta in the Supreme Court (nee House of Lords Appellate Committee) has suggested that Parliamentary Sovereignty is not as solid as one might suggest. However, that's never formed part of precedent. All that said, the scope for the Supreme Court disregarding the express will of Parliament is incredibly narrow, and that scope seems only to really be "access to justice".