This paper describes how Process Safety Management (PSM) was improved at a mature asset following a significant process safety event. An unconventional approach was adopted to enable rapid improvements drawing on the Critical Control Approach documented in Energy Safety Canada's A Barrier Focused Approach (similar to the International Council of Mining and Metals (ICMM) publication, Critical Control Management; Implementation Guide) as well as high reliability organisational (HRO) principles. The successful approach owes its intellectual origins to the concept of Safety Critical Elements (SCEs) first enunciated by the UK Health and Safety Executive following the Piper Alpha disaster. The history of the critical control approach is briefly discussed and how the original SCE idea has been enhanced. In particular, the paper will describe how the critical controls (or barriers) have been made more visible to those charged with implementing and managing them. The paper will describe the successes and difficulties of this approach including the shift in thinking required on the part of process safety experts as well as changes to organisational structure. The paper will also illustrate how the existing documentation of the critical controls was substantially reduced and rationalised to make the PSM problem (as perceived by senior managers) more manageable and sustainable. Finally, the paper will consider the extent to which well-known international PSM frameworks enhance or inhibit the adoption of this approach.