President Maithripala Sirisena's son Daham Sirisena climbed on to the stage during the prize giving of the 137th Royal Thomian "Battle of the Blues", apparently without prior invitation.
Sirisena, a former Royalist, climbed on the stage when when the prize giving was being held under the patronage of Prime Minister Ranil Wickremesinghe.
The President's son was wearing a T-shirt with the crest of Royal College.
However, several ministers and deputy ministers of the government who were in the audience watched the proceedings from outside the stage.
Meanwhile, ordinary past pupils of Royal College and St. Thomas College were kept at a fair distance by the security guards of the Prime Minister and other distrinduished guests.