A memorial service is to be held at St Paul's Cathedral on Tuesday to honour a long-serving trade union official.
Mary Turner, who died last year aged 79, was president of the GMB union and chaired Labour's national executive committee.
She worked as a school meals assistant before rising through the union ranks, and received the MBE and CBE for her campaigning work.
Tim Roache, general secretary of the GMB, said: "Our Mary was a true giant of the trade union movement and the beating heart of GMB for decades.
"This memorial reflects the great legacy she leaves as a tireless defender of working people.
"She left this world having made a real difference to so many people's lives, and that's something we are all proud of.
"Be it fighting for dinner supervisors in Brent, for hungry kids to have free school lunches, for pensions, for young people - or taking on the National Front, Mary led our movement.
"They really did break the mould when they made Mary Turner."
Warren Kenny, GMB London Region Secretary, added: "A servant to the people and hero of GMB, Mary gained the respect and recognition of everyone in GMB, the wider trade union and labour movement as well as those from all political spheres."