Update: The nature of the X of Swords: Captain Britain tie-in glimpsed during this week's episode of Marvel Comics YouTube series The Pull List has been revealed as an updated version of a previously announced collection of Captain Britain reprint stories from the 70s and 80s, by Chris Claremont, Herb Trimpe, and John Byrne.
Here's Marvel's official description of the collection, which offers some background on how Excalibur, Captain Britain and the mythology of the Otherworld tie-in to 'X of Swords':
"A legendary hero flies the flag for the United Kingdom as we celebrate the legacy of the House of Ideas with the era-spanning MARVEL TALES! In Chris Claremont and Herb Trimpe’s incredible CAPTAIN BRITAIN (1976) #1-2, Brian Braddock must choose between the Sword of Might and the Amulet of Right. Only one will transform him into Captain Britain, champion of Albion! Then, Brian takes a trip across the pond and ends up in Spider-Man’s neighborhood — but their first meeting turns downright murderous, courtesy of Arcade, in MARVEL TEAM-UP (1972) #65-66 — by the fan-favorite team of Claremont and John Byrne! Then, the sword is drawn in EXCALIBUR (1988) #1 as Claremont joins artist Alan Davis to team Captain Britain and his girlfriend Meggan with a trio of ex-X-Men - Nightcrawler, Shadowcat and Phoenix - to form the UK’s most offbeat super team!"
Original story follows
A new Captain Britain comic book will be a part of Marvel's upcoming 'X of Swords,' according to a brief visual during the latest edition of Marvel's Pull List YouTube show which promoted several upcoming September titles including those part of 'X of Swords.'
The Captain Britain title was not discussed in detail on the episode, but its cover was revealed toward the end of the video, seen in the upper right of the image here. The cover features Brian Braddock in costume as Captain Britain along with the 'X of Swords' trade dress.
This illustration by Inhyuk Lee was originally advertised to be used for Marvel Tales: Captain Britain, a collection of older Captain Britain comics scheduled for release this summer before the COVID-19 pandemic led to a distribution shutdown. That was canceled, and this image - now with the 'X of Swords' branding is now being advertised for this apparently new title.
A possible new Captain Britain title - with Brian Braddock in the title role - is particularly significant as Brian Braddock has not served as Captain Britain since the launch of 'Dawn of X' with his sister Betsy Braddock, the former Psylocke, taking on the role after defeating Brian in combat and secreting away the Sword of Might from him.
Brian Braddock, like all Captains Britain, has a connection to the Otherworld, an alternate dimension where the magic of Britain resides. The Otherworld has been a recent focal aspect of the X-Men line, particularly in Excalibur, where its connection to Krakoa and mutant-kind has been secretly exploited by Apocalypse as part of the master plan he's been enacting from the start of 'Dawn of X'.
For now, all we have for 'X of Swords''s Captain Britain is a title and cover – but more information may arrive in Marvel's full September 2020 solicitations, coming to Newsarama later this month.