Informality has long been valued in England, and this is true of the political process as well as the institution of the judiciary. In both cases, it is assumed that the senior figures will have absorbed unwritten conventions and will by osmosis naturally understand their respective role in the UK constitution. Much is now starting to change, at least as far as the English judiciary is concerned. It is, first, argued that informal judicial institutions did not become redundant when the separation of powers was formally introduced with a program of modernization of the judiciary in the Constitutional Reform Act 2005. Selected illustrations of persisting informal judicial institutions are then discussed in relation to the deliberative processes in senior courts; to judicial selection and appointments; and to the disciplinary process. Second, informal judicial institutions are deeply connected with the UK constitutional tradition. The Brexit litigation laid bare the challenges of containing political behavior within certain boundaries, and the unwritten conventions which have bound the judiciary and the executive might now be instinctively understood and shared by only one of these two parties.