Police discovered a 17 inch blade during a weapons sweep in Sydenham.
Officers uncovered the blade in Allwood Close on Saturday (July 4).
MORE TOP STORIES The Sydenham Safer Neighbourhoods Team, who found what appears to be a kitchen knife, needed two rulers to capture its length in a photograph.
Lewisham MPS tweeted the photo of the weapon with the caption '#saving lives'.
More to follow.
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