From the BBC:
"Relatives of young people who have been killed or injured by weapons have called for an end to gun and knife crime at a peace march in London. The event began at Clapton Pond in Hackney, east London, at midday, and ended with a rally at Tottenham Green, in north London two hours later."
I didn't know this event was planned and was away on Sunday anyway. So read more about it here.
P.S. As per his comment below, Ben Locker witnessed the march - with misgivings.