Expert Witness Journal Issue 67 June/July 2026 - Flipbook - Page 8
Dr Stephen Peter Castell
(3rd August 1946 – 1st April 2025)
by the family of Dr. Stephen Peter Castell.
Dr Stephen Castell, mathematician, entrepreneur,
and ICT expert witness, passed away on 1st April
2025, surrounded by family, after a battle with
cancer. For more than forty years, as Chairman of
CASTELL Consulting, he stood at the forefront of
software and systems forensics, dispute resolution,
and digital innovation. He leaves a professional and
personal legacy that will resonate for years to come.
Stephen’s work as an expert witness was
complemented by his thought leadership, and
contributions to professional publications. He
authored Computer Blu昀昀 (1983) and The APPEAL
Report (1990), a landmark study on admissibility of
computer evidence commissioned by HM Treasury.
His widely cited Cutter Consortium report (2006)
set out his forensic methodology, while later
writings explored blockchain forensics, AI, and the
legal challenges of distributed ledgers. He was a
Correspondent of the Computer Law and Security
Report and contributed frequently to conferences,
and professional journals such as this one.
Born in Cairo in 1946, Stephen’s early life re昀氀ected
his father’s RAF postings. He attended eight primary
schools and three secondary schools, including
a period in Malta. He later graduated from the
University of London with a First Class Honours BSc
in Mathematics, Physics and Psychology. He went
on to achieve an MSc and a prize-winning PhD in
Mathematics at the University of Nottingham, where
his doctoral thesis was published in full.
He remained active in technology disputes
throughout his career. In recent years he was
appointed in US class actions relating to Voyager
and FTX, advising on cases involving signi昀椀cant
alleged cryptocurrency losses. He wrote extensively
on blockchain and stablecoins, arguing for stronger
standards of digital evidence and proposing national
stablecoin models to UK government.
Stephen began his career applying advanced
mathematical modelling in industry, before moving
into management consultancy and information
systems during their formative stage. In 1978 he
founded CASTELL Consulting, which became his
lifelong professional platform. He specialised in
the strategising, planning and management of
ICT systems and businesses, and in analysing the
昀椀nancial, contractual and legal issues associated
with them.
A pioneer of Forensic Systems Analysis, Stephen
created methodologies that allowed complex IT
disputes to be understood and resolved in court. His
expertise was engaged in some of the largest and
longest-running ICT contract actions in the English
High Court and in international cases across
Europe, the USA and Australia. Notable instructions
included the Airtours v EDS litigation, the Sydney
TCard dispute, and multiple high-value arbitration
and patent proceedings. His reports were frequently
used in settlement discussions and were noted for
their clarity, objectivity, and commercial grounding.
EXPERT WITNESS JOURNAL
6
JUNE 2026
