THE decision in the conjoined appeals in UBS v HMRC and DB v HMRC [2016] UKSC 13 invites us to revisit a note published by John Tiley in 2005 concerning the decisions in Barclays Mercantile Business Finance v Mawson [2004] UKHL 51 and Scottish Provident v IRC [2004] UKHL 52 and subtitled “less chaos but more uncertainty” ([2005] B.T.R. 273). This is a richly textured piece that repays close reading; the central observation is that the cases reflected the settlement of long-running debates on the nature and scope of the Ramsay doctrine, which allows the courts to hold ineffective certain attempts at tax avoidance. As is well known, the years following Ramsay v IRC [1982] A.C. 300 itself were characterised by a tension between the need to clarify the circumstances in which the doctrine would apply and an understanding that too much clarity might allow taxpayers to circumvent the doctrine altogether.