Shami Chakrabarti, director of Liberty, said:
"Doreen Lawrence is a role model and a friend - heartfelt congratulations to her on her richly-deserved appointment to the House of Lords.
"Who can imagine transforming the grief of losing a child into a campaign to reform policing and the wider values of an entire nation? Her calm courage should be an inspiration to everyone."
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The 20-year-old was found fatally wounded on Roth Walk, near Finsbury Park, north London at around 3am on Saturday, Scotland Yard said.
Police have arrested a man wanted in connection with a burglary at the home of pensioner Richard Osborn-Brooks.
The rally comes after it emerged that the Home Office destroyed thousands of landing cards documenting the arrival of windrush-era migrants