Our sovereignty arises from the fact that we get to elect our MPs every few years. There's no "sovereignty of the people" arising from advisory referendums. If it's advisory, sovereignty remains in the hands of parliament. If I get cirrhosis and my doctor advises me to give up boozing, no matter how strong and how peppered the advice is with dire threats about refusals to give me a liver transplant, etc, my subsequent decision to nip to Sainsbury's to stock up on 25% off six is entirely legal and entirely mine. I retain sovereignty. There's no sovereignty of the doctor.