An unceasing debate in policy worlds – albeit one that surfaces in different ways – is whether you should put conflicting institutions together so they sort out their differences internally; or whether to keep them apart so their disagreements can be allowed to surface in a more open and transparent (though sometimes bad tempered) way. The answer isn't obvious.

Take one example in the news recently. Dominic Cummings, chief adviser to the Prime Minister, apparently insisted that the PM and the chancellor share political advisers rather than have their own dedicated ones. Cummings felt so strongly about this (and we must presume Boris Johnson approved) that the chancellor's threat to resign was not enough to change his mind. The result has been a Budget led not by Sajid Javid but by Rishi Sunak.