The family of Gareth Williams's family said they were "naturally disappointed" by the conclusions of the Met Police, and said they still believe he was killed.
Gareth Williams was found in a bag in the bath at his flat in Pimlico in 2010. Pathologists said he would have suffocated within three minutes if he was alive when he got inside the holdall. None of his DNA was found on the lock on the bag and his palm prints were not found on the rim of the bath.
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The meeting was arranged in the wake of Wednesday's terrorist murder of four people in Westminster.
Dozens of women gathered on Westminster Bridge to form a human chain in a show of solidarity with the victims of Wednesday's terror attack.
In a wide-ranging Peston on Sunday interview, he said Parliament security needs reviewing and the PM's counter-terror strategy is flawed.