Gregory "Greg" Barrington was hired by then Head of English Linda Radleigh to support Tom Clarkson in the classroom after she felt he was struggling with his teaching responsibilities alongside his Deputy Headteacher role.
Greg was immediately seen entering Waterloo Road acting suspiciously on the telephone, and is seen to have been a former pupil of the school.
Tom was not overly pleased with the hiring of his new teaching assistant, but Linda Radleigh assures Tom he is to purely support him in the classroom. When Linda introduces Greg to the rest of the team, Grantly Budgen immediately recognises Greg and goes on to question how it is possible when Greg is unable to read or write. Grantly is seen later on in the episode sharing that Greg is "trouble" and always was. It is hinted that Linda knew Greg on a personal level however it is unknown if this was a romance.
Greg is then seen planting a secret camera in Michael Byrne's office which later proves to be disastrous. Tariq Siddiqui becomes particularly suspicious of Greg and reports this to Tom, who attempts to investigate the situation as he could not get hold of Greg's referees. Tom later discusses his personal opinion on Michael and the school with Greg which Greg records and holds against Tom.
In a class Greg punches Tariq with Tom witnessing. It soon became apparent that the recruitment procedure with Greg was not followed when Linda hired him and he was an undercover reporter. He was shortly escorted off of the premises, Tariq not wanting the police involved.
Greg was not seen again.