On emailing classmates, that's probably trivial. Lots of school classes have Facebook pages or WhatsApp groups, or mail groups or such. These can be trivially easy to join.
These people are Russian military officers, they traveled to Salisbury, they did these things, they went back to Russia. They lied about who they are and why they went there. It doesn't really matter what the agenda of the people uncovering this is, as long as the information is valid. The question is, what should be done about it?