An uncodfied constitution can have such a thing added, just as parts of it devolved power through different docments.
The Bill of Rights placed sovereignty in the hands of parliament and the gentry, iirc, although it did spell out rights for the common man. Someone told me once, and I'm thinking it must have been the comments of a livestream somewhere because I havent seen it since and it was only n small comments with no real substance, that many of the amendments aren't lawful as they didn't go through proper parliamentary process.
