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
Who was the killer in The Sword of Guillaume? (spoiler)
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
Three spoiler-safe questions for your rewatch.
- Place
What does Causton conceal?
- Theme
Which details could have more than one meaning?
- Teamwork
Watch DCI Tom Barnaby and DS Ben Jones: who notices what?
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
Sources accompany the production credits and filming links.
Fictional settings and real filming places are listed separately. Filming links include 3 mapped areas; 6 exact sites.
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 ↗Credits follow the linked chronology. Dates can differ between territories. Consult original credits for story, teleplay and adaptation wording. External synopses may contain spoilers.
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
Follow the cast links for full actor and character guides.
John Nettles
Tom Barnaby · Detective Chief Inspector- Bergerac
- Poldark
- Royal Shakespeare Company
Jason Hughes
Ben Jones · Police Constable · Detective Sergeant · Inspector- This Life
- Marcella
- The Pact
Barry Jackson
Dr George Bullard · Police pathologist- Cathy Come Home
- Doctor Who
- Barry Lyndon
Image credits identify the licence used. No programme publicity stills are reproduced.
Forensic team
Dr George Bullard
- Credit
- Resident pathologist
- Played by
- Barry Jackson
Spoiler-controlled deaths
Deaths recorded in this case
2 people die in this case, according to the linked death record.
Break the seal: reveal the list of deaths
- Hugh Dalgleish
Murder · Stabbing or impalement
Performer check- Hugh Dalgleish: Tim McInnerny
- Jenny Russell
Murder · Stabbing or impalement
Performer check- Jenny Russell: Lucy CohuThe list of deaths prints ‘Jenny Russel’; the published cast record supports ‘Jenny Russell’, used here.
Break a second seal: reveal the verified killer
Who was the killer in The Sword of Guillaume? (spoiler)
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
Where was The Sword of Guillaume filmed?
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 accompany the identified filming places.
Wider filming areas