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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The new design is inspired by Westminster Cathedral.
Just 200 yards from Harrods, the one bedroom flat is significantly lower than the current market rate for the prestigious area.
A documentary on the career of the late London singer Amy Winehouse will be broadcast live this evening at half six.