A man told the Saville Inquiry today that, as a 14-year-old boy, he let off a cannister of CS gas close to an army barricade before Bloody Sunday.
Giving evidence to the inquiry into the killings, Mr John Duffy also claimed he was praised by a teacher for what he did on William Street about three hours ahead of the civil rights march passing there.
Mr Duffy told the inquiry he "used to riot all the time and throw stones at soldiers", adding: "That was our idea of fun."
He said he approached the barricade with a friend after attending 11 a.m. Mass as soldiers were setting it up.
"We decided to go and see what they were up to and to do a bit of heckling. None of this was any different from our normal behaviour.
"As we were having a look down William Street we decided to throw a gas cannister which we had from a previous march for a bit of craic.
"I lobbed the gas cannister and it gassed everyone in the vicinity. Just then one of my teachers came round the corner and asked who had thrown the gas cannister. I said it was me and he said: 'Good on you' and I was very proud of myself."
PA