That's the standard way of doing things in the UK and the former British Empire. Go straight from doing a Bachelor's, with coursework to doing research. He probably did the Masters programme requirements while technically an undergrad. The other interpretation is that he's part of the Ph.D. programme but he's a Ph.D. student (still doing coursework) rather than a Ph.D. candidate (gotta finish up that research and write papers/a thesis.)
It's not that uncommon in CS. I just started a Ph.D. program (Robotics at CMU) straight out of undergrad and a decent number of the other incoming students are in the same boat. It varies depending upon the field and the university. For example, several of the top mechanical engineering programs require a M.S. to apply for the Ph.D. program.