A Labour source said: "Doreen Lawrence is a hero of modern Britain. The strength and courage she has shown in her fight for justice for her son Stephen has had a profound impact on attitudes to racism and policing.
Her campaigning has changed, and will continue to change, our country for the better.
"Ed Miliband believes voices like hers should always be heard in Parliament."
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The 34-year-old victim was left with a huge gash across her nose and face. Police need to find a man seen on CCTV.
The girl was travelling on a train from London Liverpool Street to Romford in Essex after going to see the poppies at the Tower Of London.
Wealthy businessman Ivan Massow wants to succeed Boris Johnson at City Hall in 2016.