The university's study abroad office had originally prohibited the more than 300 people from MSU currently visiting London from using public transport.
Dr. Sue Carter, executive assistant to MSU President Lou Anna K. Simon, went to London to talk to students studying abroad and London officials about the ban. After she arrived, they decided buses were safe.
The information came with the help of British police and American agencies.
Two of the study abroad groups came home Friday. Three more are expected over the weekend. All will be home by mid-August.