It is completely non-sensical to expect such a nation to have a single document where the constitution is written. It's fucking easy to just write a constitution on a single piece of paper when it's done upon forming the country. It is extremely hard when you have laws going back to the 13th century and you ran a global empire up until the 1950s. It absolutely does have a constitution, and it's a constitutional monarchy, but it simply doesn't have it written on a single piece of paper.
What I'm far more interested in criticising about your idiotic comment is instead that it's just logically flawed. The critique itself originates from Princeton University, which is not a British institution, and the BBC is simply writing an opinion piece on it. Furthermore, what exactly does the BBC have to do with the politics and history of why the UK doesn't have a single piece of paper outlining its constitution? Your comment is practically just an ad-hominem.
I suppose if you wanted to make one new legally binding document making up the constitution, the UK could cancel all those laws, recreate the bits of them that make up the constitution in one single place, and then make new laws to fill in all the gaps from all the cancelled bits that weren't part of the constitution. Some of the UK constitution is procedure and books of commentary and theory, so those are going to be awkward to rewrite and put on a single piece of paper, but it could be done.
But why?
Quote from the article:
> Multivariate analysis indicates that economic elites and organised groups representing business interests have substantial independent impacts on US government policy, while average citizens and mass-based interest groups have little or no independent influence.
The study that the article talks about was published by Princeton University (in NJ). But even if it were published by Tsinghua University it would be no less valid. [Economic] science is science.
This is an interesting aside, but tell me, what's the relevance of your question to the subject at hand? It feels like veiled "whataboutism", but that would be a mean-spirited assumption to make.