R (on the application of Lanner Parish Council) v Cornwall Council [2013] EWCA Civ 1290, [2013] All ER (D) 318 (Oct)
It was an established principle that, save in exceptional circumstances, a public authority should not be permitted to adduce evidence which directly contradicted its own official records of what it had decided and how its decisions had been reached. The court could and, in appropriate cases, should admit evidence to elucidate or, exceptionally, correct or add to the reasons; but should consistently be very cautious about doing so. There would be no warrant for receiving and relying on as validating the decision evidence which indicated that the real reasons had been wholly different from the stated reasons.
