Ms Sinclair-Gieben has been in post for six years and is the eighth person to hold the post since the Prisons (Scotland) Act 1980 made the position statutory.

Stephen Sandham, the current deputy chief inspector, will step up to cover the post on an interim basis, until a permanent replacement is appointed following Ms Sinclair-Gieben’s departure.

Ms Sinclair-Gieben said: “My aim during my time has been to ensure key issues such as human rights, health, safety, and welfare are at the heart of HMIPS scrutiny and providing balanced reporting of those findings.

“I would like to thank my dedicated team for their excellent work which has made a lasting positive difference to the prison service, bringing a greater structure and rigour to the work of HMIPS.”

Justice Secretary Angela Constance said: “I would like to pay tribute and offer my thanks to Wendy Sinclair-Gieben for her long and dedicated career in the justice system. Her wealth of experience and deep understanding of prisons has enabled her to recognise and promote the needs of prisons and prisoners.

“The independent scrutiny of prisons is an essential part of our Scottish justice system and I am grateful to Ms Sinclair-Gieben for the commitment she has shown to raising challenging issues in order to improve outcomes for prisons, prisoners and the communities we serve.”