Which was the first criminal case in which the 1966 Practice Statement was used?
I think you will find that: the London Tramways case established the rule that the Lords was bound by its earlier rulings then the first case of the 1966 practice statement being applied was in a civil case of Herrington v B.R.B ( 1972 ) overruling Addie v Dumbreck (1929) so the Lords didn’t actually rush themselves into adopting the 1966 directions then the first criminal case where the statement was applied was, as you’ve said yourself the 1987 case of Shivpuri which over ruled Anderton v Ryan (1985) .. Lord Bridge remarking that, in essence, it was right to overrule the decision in Anderton despite it being only a couple of years earlier.
