One of the protesters, Chris Howson, told the Newham Recorder that arms fairs like this one were "fuelling the wars of tomorrow".
He said: "We are here to pray for peace because most people have no idea that they are selling weapons that can be used to kill women and children.”
More top news
Fighting for their right to misuse nitrous oxide, approximately 60 or 70 protesters inhaled 'laughing gas' amid concerns over a clampdown.
The pilot, from the Gnat private display team died after the display aircraft he was in crashed near the CarFest event in Cheshire.
The annual cycling festival in London was the biggest ever this year - with more than 25,000 taking part today.