Clinical team

If you would like to contact any of the individuals listed below, please contact the JAG office by email at

You can also read about the JAG office team here.

Dr Siwan Thomas-Gibson

Chair of the JAG

Dr Siwan Thomas-Gibson has been chair of the JAG since January 2017. She is a specialist endoscopist and luminal gastroenterologist at St Mark's Hospital, an honorary senior lecturer at Imperial College London and is director of education at St. Marks Academic Institute. In 2006 she was awarded an MD at Imperial College London for her work in ‘Improving Training and Assessment in Colonoscopy’. She has published over 60 scientific papers as well as National Guidelines and several book chapters. As chair of JAG, Siwan’s aims are to improve communication between JAG and clinical services; to develop JAG research and data output and to improve safety and learning from error within endoscopy.

Photo of Siwan Thomas-Gibson

Dr Christopher John Healey

Chair of the Endoscopy Services Quality Assurance Group (ESQAG)

Dr Christopher Healey was appointed as the chair of ESQAG in 2019 and is also a lead assessor on JAG accreditation assessments. Christopher trained in Medicine in Sheffield and graduated with Honours in 1987, including a distinction in surgery and psychiatry. In 1998, Christopher worked as a Senior Registrar in Cambridge before accepting his current post in 1988 as a consultant gastroenterologists in Keighley, West Yorkshire. Since 2007, Dr Healey has taken part in general medicine and has since become a NHSBCSP colonoscopists, before joining the JAG team as an assessor in 2009. 


Dr Geoff Smith 

Chair of the Quality Assurance of Training Working Group (QATWG)

Geoff Smith is a luminal gastroenterologist at Imperial College Healthcare NHS Trust in west London. He has been a screening colonoscopist for over 10 years and is faculty on Colonoscopy training courses at St George’s Hospital. He is also Deputy Postgraduate Dean for North West London, Chair of the Exam Board for the European Specialty Examination in Gastroenterology and Hepatology, and was recently appointed as Chair of the Bowel Cancer Screening MCQ group. His academic interests focus on cognitive load in skills training and the development of training systems for complex medical interactions such as ward rounds. 


Debbie Johnston

Head of Assessors

Debbie Johnston is the head of assessors, providing expert leadership to over 30 assessors, ensuring consistent application of the JAG standards, and assessments of the highest possible quality. She has over 30 years’ experience in healthcare in nursing, managerial, quality improvement and quality assurance roles, and has played a key role in the development of the JAG scheme since its establishment in 1994. Debbie has developed advanced skills in many areas, including: training and leadership skills development; quality improvement; assessor training and development; change management; programme and business management skills.

 Photo of Debbie Johnston

Helen Griffiths

Deputy Head of Assessors

Helen Griffiths is a retired nurse consultant with over 25 years’ experience in gastroenterology. She continues to work part time as an endoscopist and trainer at Wye Valley NHS Trust. Her doctorate and special interest is in Barrett’s oesophagus, supporting master classes and training in this area. Appointed as deputy head assessor for JAG in 2017, she has worked as a JAG assessor and lead assessor since 2007. Helen is the decontamination advisor for the BSG and represents nurses on a number of working parties for BSG clinical guidelines and guidance documents. She lectures nationally and internationally in gastroenterology and advanced nursing practice, and represents the profession and specialty on a number of medical and nursing committees.

 Photo of Helen Griffiths

Dr Brian McKaig

Chair of Bowel Cancer Screening Programme (BCSP) Accreditation Panel

Dr Brian McKaig is the chair of the BCSP Accreditation Panel, having been a bowel cancer screening colonoscopist and assessor for over 10 years. He represents the BSG on the National Advisory Committee for Bowel Cancer Screening and is the professional clinical advisor (colonoscopy) for the West Midlands Bowel Cancer Screening QA service. He is co-director of the West Midlands Regional Endoscopy Training Centre and have an active role in the JAG developing training pathways as part of the JAG QA of Training Working Group. Brian is associate medical director for Royal Wolverhampton NHS Trust with a lead role in consultant appraisal, revalidation and job planning and has a specialist interest in advanced colonoscopy and endoscopy training.

Photo of Brian McKaig

Professor Matt Rutter

Chair of the National Endoscopy Database (NED) working group

Professor Matt Rutter is professor of gastroenterology at Durham University, specialising in advanced diagnostic colonoscopy, polypectomy and IBD. Matt leads the group developing the National Endoscopy Database (NED)

Photo of Matt Rutter

Dr James East

Chair of the JAG research committee

Dr James East is a  gastroenterology and clinical lead at Oxford University Hospitals and is also the Director for the Oxfordshire Bowel Cancer Screening programme.

James joins JAG to chair the new JAG research committee.



Phedra Dodds

JETS Workforce lead

 Phedra Dodds has been chair of the Welsh Endoscopy Nurse Training faculty since 2015 and has focused on quality improvement as part of the national endoscopy team where she was lead nurse from 2002-2015. Phedra is responsible for providing leadership and direction for the JETS workforce training programme and leads on the implementation of competency framework and training packages.

Beverley Raven 

JAG Nurse lead

Beverley is an experienced JAG assessor and has over 20 years of endoscopy experience working with senior management teams across the NHS, most recently as the national endoscopy lead for Ramsay health care. Beverley has an important role leading on the production of guidance for services and working with the JAG leadership team. Part of Beverley’s role is to provide nursing expertise to the JAG, with a particular focus on environment and the nursing workforce.

Jon Walton

Training centre and course QA lead 

Jon has been working within the NHS for over 10 years withthe last 4 years of this as the Endoscopy Clinical Auditing and Training officer within St Mark’s Hospital in London. He is responsible for the coordination and delivery of the JAG certified courses within the trust, he is also primarily responsible for all departmental auditing relating to JAG as well as the cross-site completing of GRS annually as well as site visits.

He has previously worked for the Hertfordshire Partnership University NHS Foundation Trust within mental health specifically looking at how best to quality assure service users experience and expectations of services.

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