Layers of Risk: Understanding Use of Force Through the Swiss Cheese Model

ICPA 2025 Presentation by Grant Bosworth and Sarah Ashcroft (PID233)

Authors

Grant Bosworth

Head of Insights and Assurance, Operational Response and Resilience Unit, HMPPS, England, United Kingdom

Dr. Grant Bosworth leads the Insights and Assurance team at His Majesty’s Prison and Probation Service (HMPPS), overseeing the monitoring and assurance of Use of Force across adult and youth custodial settings in England and Wales. With a PhD in behavioural psychology and a background in research methods and economics, he encourages an evidence-based approach to prison research and assurance.

He has co-authored a vision for professional standards in Use of Force for HMPPS (Prison Service Journal, Issue 252) and led a first-of-its-kind review of over 160,000 incidents of force from 2018–2023, now published by the Ministry of Justice on gov.uk.

Sarah Ashcroft

Head of Operational Response and Resilience Unit and International Engagement Lead, HMPPS, England, United Kingdom

Sarah Ashcroft serves as Head of the Operational Response and Resilience Unit and International Engagement Lead at His Majesty’s Prison and Probation Service (HMPPS). With extensive experience across multiple levels of the prison service, she plays a pivotal role in shaping national policy and operational readiness.

Sarah is responsible for Use of Force policy and oversees the deployment of the National Tactical Response Group—a specialist unit tasked with responding to the most challenging incidents in custody, including hostage situations. She co-authored the national vision for professional standards in Use of Force, published in Prison Service Journal, Issue 252, and continues to lead efforts to ensure safety, accountability, and resilience across the estate.

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