He was asked by the head of MI6 to assist Dr. Helen Magnus and John Druitt in recovering an ancient artifact (actually the keystone needed to unlock the holographic city). He brought them to one of the museum's vaults and gave them the artifact; he also noted that John Druitt bore a resemblence to someone, but before he could finish, Druitt and Magnus teleported away while his back was turned.
However, they soon discovered that the artifact he gave them was just a copy, as it lacked the gamma radiation emitted by the real keystone. Druitt returned to the museum, grabbed the curator, and teleported him to the peak of Big Ben, threatening to drop him. The curator quickly confessed that he was secretly selling artifacts from the museum after replacing them with copies. He also gave them the whereabouts of the real keystone's buyer in Hong Kong.