It seems that before Captain Britain appears as a Secret Avenger, he first appears in Uncanny X-Force #20.
The plot for this story is...
The Trial of Fantomex Part 1
The X-FORCE team journey to OTHERWORLD!
Guest starring CAPTAIN BRITAIN and the CAPTAIN BRITAIN CORPS!
Things do not look good for Fantomex. He has been charged with premeditated homicide and abducted from the X-Cavern by Captain Britain to stand trial in Otherworld. Captain Britain also abducted Psylocke in an effort to "save" her from her "horrible life as a member of X-Force".
While Deadpool, Wolverine and AoA-Nightcrawler get acquainted, they are interrupted by Ultimaton, who informs them of the abduction of Fantomex and Psylocke.
How did Captain Britain know about Cavern-X?
What is the real reason he wants his sister back in Otherworld?
Who is behind the battle for Otherworld?
How were Fantomex's actions known to the Supreme Omniversal Tribune of Otherworld?
Will Wolverine figure out where his teammates have been taken?
Will Deadpool and AoA-Nightcrawler get along?
All this and more awaits, in Chapter One of this new Uncanny X-Force story arc!
Thank you to Comicvine for this synopsis.
Yet again he's depicted in his 80's costume, plus the picture at the top of this blog also has Meggan, and do my eyes deceive me... is that Betsy Braddock in her, short-lived stint as Captain Britain?