He stood as an independent and became London’s first mayor in May 2000, when then-Prime Minister Sir Tony created the powerful post.
In his second term, which he won as an official Labor candidate, he received praise for the way he defended London after the July 2005 suicide bombings and helped win the 2012 Olympic Games for the capital.
Livingstone lost the City Council in 2008 when he was defeated by an equally colorful opponent, Boris Johnson, and a failed attempt to return to office in 2012 marked the end of his electoral ambitions.
He became embroiled in a series of anti-Semitism accusations, leading to his departure from the Labor Party in 2018.
It came after a long dispute over his claims that Adolf Hitler had supported Zionism in the 1930s, which had originally seen him suspended from the organization in 2016.
The former Brent East MP was singled out in a 2020 human rights watchdog report into how Labor dealt with allegations of antisemitism, which said Jewish members of the Labor Party felt he had made comments that “had the effect of stir up and fuel hatred towards Jews.”
On Tuesday it was reported that Livingstone withdrew a legal challenge against the Equality and Human Rights Commission report.
The Alzheimer’s Society praised his family for “being open about his diagnosis.”
Chief executive Kate Lee said: “We are very sorry to hear that Ken Livingstone is living with Alzheimer’s disease. Our thoughts are with him and his family.
“We can see how prevalent dementia is in high-profile people who have recently spoken out about their dementia diagnosis, including Alastair Stewart and Fiona Phillips, among others. One in three people born in the UK today will develop this devastating disease.