Mark Seymour

Mark Seymour

Prosecutes and defends fraud and serious crime.



MA (Hons) Law from Jesus College, Cambridge


CPS London Advocate Panel Grade 4
CPS Specialist Fraud Division Panel at Level 4
CPS Serious Crime Panel at Level 4
CPS RASSO specialist rape prosecutor at Grade 4
SFO Advocate Panel Grade A


Criminal Bar Association
South Eastern Circuit
Surrey and South London Bar Mess
Proceeds of Crime Lawyers Association
Fraud Lawyers Association
Middle Temple
Direct Access Qualified

Overview of Practice

Mark is a highly-experienced, highly-regarded advocate and lawyer with over 20 years’ experience of prosecuting and defending at the Criminal Bar.  Mark prosecutes and defends in the most serious and complex cases of fraud and serious organised crime.  He prosecutes and defends both as a Leading Junior and a Junior alone.  His practice is predominantly in the Crown Court, but also when required in specialist proceedings before the Magistrates’ Court.  He has extensive experience in Police Discipline proceedings.

Practice Areas

Mark is an advocate with a reputation for meticulous preparation and attention to detail.  His advocacy style is one that holds the attention of the jury who appreciate his structured yet persuasive approach.  His written work is of the highest quality.  He is renowned for working extremely hard for each and every professional or lay client, engaging with them to get the best possible outcome.


Clients and Solicitors alike appreciate the depth of analysis and understanding of strategy that Mark brings to every case in which he is instructed.

As a result of his substantial experience in serious cases, Mark has particular strengths in the collation, analysis and where necessary presentation of complex surveillance, telephone network/download/cell-site material, and also tachograph and sat-nav evidence.  Mark has extensive knowledge of dealing with the complex disclosure issues arising in serious, complex cases including those connected with PII and RIPA material.


Mark is currently appointed at Grade 4 to the Organised Crime Division Specialist Panel, and has been since 2011.  That appointment was underpinned by his appointment between 1996 and 2006 to the “Customs Lists”, culminating in some years at List A of the AG’s List of Prosecution Advocates.  As a result Mark has appeared in a significant number of trials involving multi-handed drugs importation and supply of substantial quantities of Class A and B drugs, both in a leading and junior capacity.  Mark was recently commended by the Court of Appeal for his exemplary handling of complex, sensitive Disclosure/PII issues in a massive multi-lorry Class A international drugs conspiracy.

Mark is frequently called upon to prosecute the full lexicon of serious crime, including s18, Armed Robbery, Aggravated Burglary, Blackmail etc.

Immigration crime: Mark has been instructed recently on a number of occasions on behalf of those charged with immigration fraud/people trafficking.  Mark secured significant success in the well-known Court of Appeal immigration facilitation case R v Kapoor.

Financial fraud constitutes a significant proportion of Mark’s practice. This has included lengthy, high-value cases of significant complexity, volume and seriousness. During 2016 Mark successfully defended (led by Alexandra Healy QC) the First Defendant in a 3-month 15-handed £40m mortgage fraud. He is adept in the handling of cases which involve very substantial volumes of evidence and disclosure, and has the IT skills to master the material involved in such cases.

In recent years Mark has had significant experience in prosecuting multi-£m VAT, Tax, Duty Evasion and Insurance fraud, Cheating the Revenue, and Money Laundering. Mark is currently appointed at Grade 4 to the CPS Specialist Fraud Division Panel. He is often called upon to advise pre-charge in complex cases. Mark has also been frequently instructed to prosecute corporate fraud, and internal theft/corruption.

Between 2005 and 2007, Mark was seconded full-time by HMRC / RCPO as Counsel to a dedicated Project set up to conduct a retrospective review of the adequacy of disclosure in a substantial number of historic prosecutions for Drugs, VAT and Money Laundering offences connected with allegedly corrupt informant-based intelligence derived from the part-HMRC regulated MSB sector. As a result, Mark has particular expertise in financial cases involving complex disclosure/PII issues.

Mark has prosecuted and defended in numerous substantial confiscation proceedings, particularly those following substantial multi-£m fraud and drugs prosecutions. He has an extensive in-depth knowledge of the current and historic confiscation schemes under POCA 2002 and the CJA 1988. He has appeared in the Court of Appeal in a number of confiscation cases for both prosecution and defence. His experience has led to instructions to act specifically in connection with large-scale multi-£m confiscation cases arising from fraud, regulatory, and drugs prosecutions.

Mark also receives instructions in connection with restraint and enforcement proceedings. He was recently instructed in substantial 3rd party enforcement proceedings arising from substantial confiscation £8m orders consequent upon a successful £25m VAT fraud that he prosecuted.

Mark has acted on a number of occasions for prosecuting authorities in connection with Magistrates’/Crown Court cash confiscation proceedings, including cases involving very substantial quantities (£1m+) of seized cash.

Mark has a particular expertise in Local Authority regulatory prosecutions, working for a variety of local authorities throughout the London area (in particular WCC) in connection with the more serious offences in the fields of Food Safety, Trading Standards, Licensing, Environmental Health, Planning and Education in the Crown & Magistrates’ Courts.

Mark has also defended in the Crown Court those charged with serious health and safety, and trading standards breaches.

Mark has extensive experience throughout his career both defending and prosecuting in Police Misconduct proceedings. This includes proceedings in most Police forces throughout SE England, and some further afield. This has included multi-Officer and in some cases multi-hearing Misconduct Proceedings of substantial length and complexity. Mark also advises Police Forces in relation to all aspects of Police Misconduct proceedings.

Mark has also appeared on a number of occasions in proceedings before the Police Appeals Tribunal, both on behalf of Officers and Police Forces.

His experience and knowledge have resulted more recently in appointment as a Legal Adviser to Police Tribunals.

Mark has advised upon and appeared in connection with Divisional Court Judicial Review proceedings arising from Police Misconduct proceedings.

Mark has frequently appeared on behalf of Police Officers in criminal proceedings ranging from assault matters in the Magistrates’ Court right up to lengthy Crown Court trials.

Mark also has experience of representing Police Officers in Inquest Hearings.

He also has significant experience of appearing in the Court of Appeal and the Divisional Court (both in Judicial Review and Case Stated).

Notable Cases

R v Hussain & Ors (Snaresbrook CC, 2017) – Successful defence of leading Def in multi-handed Firearms trial.

R v Khan & Anderson (Central Crim Ct, 2016) – Successful prosecution of Defs involved in encouraging terrorism by distribution of pro-ISIS leaflets on Oxford Street.

R v Gaffney & Ors (Blackfriars CC, 2015) – Instructed as Leading Junior to prosecute 12x handed, 5-week, sensitive Prison Mutiny at HMP Highdown, involving inmates protesting against prison cuts/regime.

Op Aquamarine (Southwark CC 2016) – Successful acquittal defending 1st Def in 15x handed £40m mortgage fraud. Trial lasted 3m + 3m.

R v Ewere & Ors (CCC, 2015 – 2016) – Successful ML prosecution involving the receipt, breakdown and distribution of significant funds resulting from both a phishing fraud and a romance fraud.

Op Beechbox (Canterbury CC, 2012 – 14) – Successful prosecution leading for Crown prosecuting 3x Silks in relation to a substantial, complex 3-handed £2m ghost-brokering insurance, tax and money-laundering fraud.

Op Chondrite (Maidstone 2014) – Successful prosecution of multi-£m multiple-import duty evasion fraud in which the primary evidence was 000s of Satnav/Cell-site/Tachograph/ANPR mapping points, presented to jury using specialist software via Court video screens.

Op Colinear (Kingston CC 2010 – 14) – Successful prosecution of complex £25m VAT fraud against Silk following lengthy abuse of process hearing. Defendant was sentenced to 8 years imprisonment, following which I lead for the Crown in relation to significant confiscation proceedings.

R v Biryah & Ors (2007 – 09) – Instructed as leading junior to prosecute £5m 3-handed 6 wk Conspiracy to Cheat/Tax fraud trial through construction labour supply business.

Op Footloose (Southwark CC, 2005) – Instructed alone (Silk re abuse) to prosecute international money-laundering conspiracy involving c.£1.25m drugs cash channelled through London BDCs by South American cartel.

Op Solon (Ipswich CC & CA, 2013 – 16) – Successful prosecution and appeal in 3-handed c.9m Conspiracy in relation to 3x lorry drivers importing c.£40m worth of Class A & B drugs. The case went to the Court of Appeal where, after the lifting of PII, and upon my Advice, the Crown resisted the appeals on the basis of fresh German intercept evidence which effectively demonstrated that the case advanced at trial and on appeal was nonsense.

Op Sabden (Croydon CC, 2010 – 12) – Successful prosecution as Leading Junior of c.9 week complex 8x handed 12kg/£4m Class A drugs importation/supply conspiracy.

Op Caroche (2009 – 2010) – High-profile, complex SOCA investigation 12-handed £36 million boat drugs importation which hit national headlines following conviction of the bulk of the Defendants.

Op Millipede (Kingston 2015) – Bespoke disclosure review.
R v Mahi & Ors (Isleworth CC, 2017) – Prosecution of youth gang members for Rape and Controlling Prostitution of 15 yr old Compl.

R v Von-Stumm (Snaresbook CC, 2016) – Prosecution of intra-relationship Rape involving complex evidence/disclosure against Silk.

R v Coughtrey (St Albans CC, 2015) – Successful prosecution of Def charged with 25x Cts of historic Rape and serious sexual offences against 5x related, young, male and female Complainants, severely affected by offences committed against them.

R v Van Puyenbroek & Ors (Op Solon) [2016] EWCA Crim 1364, CA – Commendation received re conduct of PII/disclosure in multi-£m Class A lorry importation conspiracy.

R v Pepple [2016] EWCA Crim, CA – Evidence of purported fresh evidence of Compl in Rape case having admitted to lying in evidence at the trial.

R v Drinkwater [2016] 1 Cr. App. R. 30, CA – Admissibility of evidence at instance of Defence re confession of deceased 3rd party to crime of which Def charged.

R v Dhall [2013] EWCA Crim 1610, CA

R v Cortes Plaza [2013] EWCA Crim 501, CA – Admissibility of evidence of single recent conviction for drugs importation as bad character in drugs importation/supply conspiracy.

R v Sakhizada [2012] EWCA Crim 1036, CA – Standard of proof in confiscation proceedings where Crown rely on evidence of criminality outside the scope of the indictment.

R v Kapoor (Saran Singh) [2012] 2 Cr. App. R. 11, CA – Successfully demonstrated that immigration offence of which Def purportedly convicted in Crown Ct, did not exist in law.

R v Sixto [2012] EWCA Crim 2615, CA – Admissibility of evidence re bad character of 3rd party pursuant to s100 CJA 2003.

R v Muia [2012] EWCA Crim 332, CA – Causation in local authority confiscation proceedings.

R v Mileusnic [2010] EWCA Crim 2298, CA – Directions to jury re falsity of documents relating to Def’s presence on vehicle used to import drugs to UK.

R v Murrell [2005] EWCA Crim 382, CA: pre-CJA 2003 – Admissibility of evidence re bad character of Def at the instance of Co-Def.

WCC v FCUK Retail Ltd. (2005) 169 JP 321, [2005] EWHC 933, DCt –
Regulation of noise pollution from storefront glass loudspeakers in a London street.

R v O’Brien [2003] EWCA Crim 1370, CA DCt – Sufficiency of evidence re identification.

WCC v McDonald [2003] EWHC Admin 2698, DC – Sufficiency of evidence of Local Authority Officers re noise nuisance.

R (Vickers) v West London Mags Ct (2003) 167 JP 473, DC – Availability of reasonable excuse in response to remand for breach of bail conditions.

R (on the application of Graham) v DPP [2003] EWHC 120 (QB) – Sufficiency of evidence of Police Officers in prosecution for speeding.

R v Inner London Cr Ct, ex p. N & S [2001] 1 Cr. App. R. 343, DC – Factors to be taken into account in determining appropriate length of Detention and Training Order.

R v Condron [1997] 1 Cr. App. R. 185, CA – The first, and still the leading case, on adverse inferences from silence in interview pursuant to s34 CJPOA 1994.