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.”
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With just three days to go until polling stations open, representatives from all parties were out in force across the capital today.
The garden above the Canary Wharf Crossrail station is now open to the public.
First time buyers in London now need an average annual income of £77,000 - nearly double the amount required in the rest of the country.