Murphy is making his usual two mistakes, of not understanding the economics nor the logic.
On the economics he’s missed that GDP, and thus the size of the economy, is production, or consumption, or income. Each of which will be, by definition, equal (absent people lying about tax of course).We thus don’t need the exact and precise details that he’s mumbling about because we can estimate from a combination of the different methods. As the ONS actually does to reach those GVA (GVA is roughly equivalent for GDP for a sub-national area) numbers at the three NUTS levels.
He’s also wrong in logic of course. He’s the proponent of the Courageous State idea, which is that the government should take a much more heavy handed approach to the management of the economy. Lots of lovely planning and firm state action. And yet here he is insisting that the government really has no clue, not a scoobie, about the state of the economy at anything less than UK level. Something which would make that detailed planning a tad difficult one would think. But then the internal contradictions of his own arguments are not really something that trouble Professor Murphy. Perhaps there’s a whiff of ermine in the air?