Walter Reppion was an agent from the British intelligence agency S.T.R.I.K.E. and liaison to the U.N. Security Council who was planted as part of the ambassador entourage invited to Xavier's Jerusalem Habitat. He along with the other member's were greeted by the Stepford Cuckoos and Magneto who took over the task of giving the ambassadors a tour through the various biomes of Krakoa.
As they came to the end of the tour, Sophie read the minds of the delegates along with Reppions and conveyed to Magneto that they were not ambassadors at all but were sent there to spy on the mutants to determine the validity of their new found nation-state and its relationship to humanity. Reppion's true allegiance were revealed but his only assignment was to watch and observe the situation.