Capt. Britain: Brian Braddock's life was planned for him from before he was even born. Merlyn sent his father James Braddock to Earth to sire a champion who could defend the multiverse. As a young man, Brian Braddock visited America in a student exchange program, rooming with Peter Parker (a.k.a. Spider-Man), alongside whom he faced the assassin Arcade and the lycanthropic menace know as Litter.
Juggernaut: Excalibur's earliest escapades found them preventing Juggernaut from escaping prison, and taking on the Crazy Gange and Arcade in his deadly "Murderworld". Who could have imagined that years later, due to the decimation of the mutant population following "M-Day," that the unstoppable Juggernaut, would journey to England and become a trusted member of team Excalibur.
Nightcrawler: Kurt Wagner was shunned at birth due to his demonic appearance, which included blue skin, pointed ears, fangs, and a long pointed tail. Nearly dying during the massacre of the Morlock population by Riptide, Kurt was taken to the Muir Island mutant research facility to recuperate. Lead to believe that the X-Men had died in Dallas at the hands of Adversary, Kurt carried on, later becoming one of the founding members of the British super-team, Excalibur.
Meggan: Meggan and Brian Braddock (a.k.a. Captain Britain) helped found Excalibur. After defeating Mastermind, Brian was crowned King of Otherworld, with Meggan as his queen. The pair recently returned to their own world (Earth-616) during a reality storm, and Meggan appeared to sacrifice herself to seal an interdimensional rift, thus preventing the reality disruption from spreading across the multiverse.