Case file · Series 13, Episode 1 · Season 13, Episode 1
The Sword of Guillaume
A Causton business trip to Brighton ends in a ghost-train beheading and introduces Tom to his cousin DCI John Barnaby.
The 60-second case card
Should I watch this one?
The seaside case expands the programme's geography and quietly introduces the detective who will inherit it.
- Best for
- Brighton · John's introduction · Civic trip
- Archive category
- Landmark
- Team
- DCI Tom Barnaby with DS Ben Jones
- Spoiler guidance
- Read the premise freely; open the marked sections only after watching. Check the linked provider advisory for further viewing information.
Why it matters
The seaside case expands the programme's geography and quietly introduces the detective who will inherit it.
Causton Mayor Dave Hicks proposes a Chamber of Commerce reunion in Brighton while promoting a coastal land purchase that Tom Barnaby considers suspicious. During the trip, unpopular developer Hugh Dalgleish is beheaded on a pier ghost train.
Tom works with Brighton DCI John Barnaby—his cousin—to investigate civic figures, business interests and the history of the ceremonial sword that travels with the Causton delegation. Jones and Gail's attempted evening off proves no more peaceful than the official excursion.
Break the seal: reveal the finding
The land deal and the sword's disputed history link Causton ambition to the Brighton murders. The two Barnabys combine local knowledge with coastal police evidence to expose the scheme.
Spoiler-safe viewing companion
Three questions to carry into the episode
Use these spoiler-safe prompts to notice the setting, the investigation and the details that may matter.
- Place
How does Causton and Brighton shape what people say openly, delay, or leave unsaid?
- Theme
Which details seem to carry more than one meaning, and what might be a red herring?
- Teamwork
Compare how DCI Tom Barnaby and DS Ben Jones gather information: who watches the room, and who presses the conversation forward?
More episode detailsProduction, cast, deaths and filming information
Credits, context and checked facts
Production and cast
- TV series
- Series 13
- Episode number
- Episode 1
- Written by
- Michael Aitkens
- Directed by
- Renny Rye
- Listed transmission date(s)
- 10 February 2010
- Reported filming period
- July–August 2009
- Detective
- DCI Tom Barnaby
- Partner
- DS Ben Jones
- Pathologist
- Dr George Bullard · Barry Jackson
- Principal setting
- Causton
- Casebook tone
- Landmark
Check the credits, then follow the source trail for production and filming details. Counts below describe this archive’s records.
The fictional setting and the real filming sites are separate pieces of information. The location desk currently connects it to 3 broader filming areas and 6 exact on-screen site identities.
Credits and archive connections
- Writer credits9 episodes credited to Michael Aitkens
- Director credits23 episodes directed by Renny Rye
- Release positionCase 74 of 144
- Story characterLandmark · Brighton · John's introduction
- Location evidence6 exact screen-use matches
Neil Dudgeon debuts as DCI John Barnaby one series before becoming the programme's lead.
The Royal Pavilion, Town Hall, Grand Hotel, Palace Pier and West Pier ruins appear under their real identities.
Sources for the production file
Published episode chronology and credits ↗Official ITV programme page ↗Filming-location reference index ↗The chronology is the reference for the credits shown here. A programme homepage does not independently verify a filming date or every production detail. Where multiple transmission dates are listed, territory attribution needs checking. Story, teleplay and adaptation distinctions require the original credit wording; links to external synopses may reveal plot details.
Selected episode credits
The Sword of Guillaume cast
These selected cast entries link to their published profiles. They do not include every name shown in the end credits.
Tim McInnerny
Hugh Dalgleish is encountered during the Brighton excursion that expands the case beyond Midsomer. McInnerny's polished presence fits an episode built around civic ceremony, hidden connections and the handover between Barnaby generations.
Open actor profile →
Mark Gatiss
Gatiss plays the Reverend Giles Shawcross in The Sword of Guillaume, the case that takes Barnaby's investigation to Brighton. His role adds a familiar writer-performer's face to the episode's unusually broad setting.
Open actor profile →Jane Wymark
Neil Dudgeon
Kirsty Dillon
Brian Capron
Robin Soans
Saskia Reeves
Lucy Cohu
Colin Brummage
Julia Watson
Rosina Carbone
Janet Suzman
Darren Tighe
Billy Geraghty
James Greene
The performers behind this case
Core cast
Actor profiles for the detective, investigating partner and pathologist credited to this episode.
John Nettles
Tom Barnaby · Detective Chief InspectorAn English actor, author and narrator who was already a household name as Jersey detective Jim Bergerac. After Bergerac he spent five seasons with the Royal Shakespeare Company and later returned to television drama in Poldark.
- Bergerac
- Poldark
- Royal Shakespeare Company
Jason Hughes
Ben Jones · Police Constable · Detective Sergeant · InspectorA Welsh actor who first became widely known as Warren Jones in the BBC drama This Life. His later television work includes Marcella and The Pact, alongside substantial theatre work at venues including the Donmar Warehouse and Royal Court.
- This Life
- Marcella
- The Pact
Barry Jackson
Dr George Bullard · Police pathologistAn English stage and screen character actor whose career lasted more than five decades. His credits ranged from the landmark television play Cathy Come Home to Doctor Who, Barry Lyndon and many familiar British television dramas.
- Cathy Come Home
- Doctor Who
- Barry Lyndon
Portraits are used only where a reusable licence or public-domain release has been verified. Publicity stills and stock photographs are not copied into this independent guide.
Forensic desk
Dr George Bullard
- Credit
- Resident pathologist
- Played by
- Barry Jackson
Causton's long-serving pathologist is professionally unflappable, quietly witty and an old friend of Tom Barnaby.
Meet the Casebook pathologists →Spoiler-controlled deaths desk
Deaths recorded in this case
2 people die in this case, according to the linked death record.
Break the seal: reveal the death ledger
- Hugh Dalgleish
Murder · Stabbing or impalement
Performer check- Hugh Dalgleish: Tim McInnerny
- Jenny Russell
Murder · Stabbing or impalement
Performer check- Jenny Russell: Lucy CohuThe body-count ledger prints ‘Jenny Russel’; the published cast record supports ‘Jenny Russell’, used here.
Break a second seal: reveal the verified killer
Verified killer
Marcia McIntyreMarcia killed Hugh Dalgleish and Jenny Russell with the Sword of Guillaume after hearing the plan to use Jenny to continue Richard William's family line. She created the anonymous letters and hooded figure as a false trail, then attacked Giles Shawcross when Barnaby interrupted her intended next killing.
Verified motive
Marcia had devoted her life to Richard and acted from love, betrayal and fear of losing him when she overheard the scheme to use Jenny to continue his family line. She set out to eliminate Dalgleish, Jenny and the other participants, while the religious staging and sword supplied her false trail and chosen symbolism.
Verified important clue
Archive case 74 · checked 16 September 2026Marcia McIntyre's Oxford yearbookThe yearbook places Marcia, Richard and Giles together before Richard's disabling attack and exposes the concealed relationships around him; that history, combined with the threatened inheritance scheme, explains Marcia's victim selection while the religious letters remain a false trail.
Verified decisive clue
Archive case 74 · checked 17 September 2026Marcia McIntyre's Oxford yearbookThe yearbook places Marcia, Richard and Giles together before Richard's disabling attack and exposes the concealed relationships around him. Read with the inheritance plan, it explains Marcia's two murders and interrupted attack on Giles while leaving the anonymous religious letters and hooded figure as staging.
Verified death and discovery order
Archive case 74 · checked 16 September 2026- discoveryA plan to continue Richard's family line is overheard
Marcia learns that Hugh, Jenny and their circle intend to use Jenny to provide Richard William with an heir.
- deathHugh Dalgleish is killed
Marcia begins eliminating the people behind the plan, using the Sword of Guillaume as both weapon and symbol.
- discoveryLetters and a hooded figure create a false trail
Anonymous warnings and religious staging divert attention from Marcia's personal grievance and intended victims.
- deathJenny Russell is killed
Marcia kills Jenny because the proposed family-line scheme made her the central threat to Marcia's place beside Richard.
- discoveryThe sword links the staged killings
The historic blade and the shared family-line plan connect the two deaths rather than the anonymous religious warnings.
- discoveryThe next attack is interrupted
Barnaby stops Marcia as she attacks Giles Shawcross, leaving two completed murders and exposing the false trail.
Real place → fictional identity
What was filmed where?
St Mary's Church
Used as: The church appears as the Midsomer Parva church where Sir Guillaume is buried.
Royal Pavilion and Brighton seafront
Used as: The Pavilion, Town Hall, Grand Hotel and both piers appear under their real Brighton identities.
Former NatWest Bank
Used as: The building becomes The Shires Bank.
Representative photograph of the real filming location; the exact camera angle or building may differ.The Coy Carp
Used as: The canal-side pub is used for Jones and Stephens' interrupted meal.
St John the Baptist Church
Used as: The church provides the interior of Midsomer Parva's church.
Representative photograph of the real filming location; the exact camera angle or building may differ.
Newington House
Used as: The house becomes the Guillaume family home.
Representative photograph of the real filming location; the exact camera angle or building may differ.Sources support the listed site uses; they do not establish every filming location in an episode.
Wider filming areas
Places connected to this file
Wallingford
One of the principal doubles for Causton, with its Corn Exchange, riverside and civic streets appearing repeatedly.
Open location →Chesham
The old town, church, market square and shops have doubled for Causton and several fictional villages.
Open location →Little Missenden
A recurring village double whose streets, church, manor and Red Lion helped establish the look of Badger's Drift and later communities.
Open location →