In a powerful speech, the TV personality, who has become an outspoken critic of left-wing antisemtism -particularly on Twitter - reeled off a shocking list of abusive names she has been called online.
"In the name of Labour I've been called a hypocrite, lying propagandist, tits, teeth and ass clothes horse, dolly bird, weaponiser of antisemitism, fascist, right-wing extremist, Nazi sympathiser, Twitter cancer, thick Tory, brainwashed, an anti-Semite, white supremacist, hate preacher, Zio political trollster, not a real Jew, a child bully, conspiracy theorist, a paedo-protector minion puppet who my dead grandfather would be disgusted by."
She said the abuse had all the signs of being from committed "neo-Nazis" but instead the offensive names were tweeted by people whose profiles featured "the red Labour rose coupled with the Palestinian flag and the hashtag of Get the Tories out and Jeremy Corbyn for PM, along with the standard claim to be against racism in all forms" as their "signature give aways".
Insisting that her own Jewish identity had been a "confusing one" Ms Riley joked that while her mother was Jewish, "my dad's Man United".
But as a cultural rather than religious Jew, she recalled visiting Auschwitz for the first time last November.
"I've never experienced the feeling of being punched emotionally in the stomach like I did standing by that display," said Ms Riley of the videos shown in the Shoah exhibition at the death camp of Jewish families going about their ordinary lives in the 1930s.
She had formerly believed antisemities were only like the Nazis, but this view had changed in the aftermath of the Enough Is Enough demonstrations in Westminster last year.
She began to see open displays of the emergent left-wing antisemtism such as posters on bus stops declaring "Israel is a racist endeavour" as a response to Jeremy Corbyn's failure to adopt the full IHRA antisemtism definition.
Ms Riley felt she has been targeted for highlighting antisemitism in the Labour Party and acknowledged that speaking out could damage her TV career. Yet those attacking her spoke with impunity.
"One misplaced word from me could be ruinous. No one should have to jeopardise their safety or their careers speaking out against antisemitism. We need to remember our history."
She said she was trying to educate herself on the topic, watching six hours of videos on Christmas Day on the history of antisemitism and had spoken to a range of people, Labour MPs among them.
She suggested that “knowledge and truth are our only weapons” in tackling the problem, adding: “You need to know next to nothing to propagate Nazi or Soviet Jew-hating propaganda reframed to fit today’s narrative, which spreads like wildfire and is dangerous.
“But you need to know nearly everything to stop it. The odds are stacked in the antisemite’s favour.”
Home Secretary Sajid Javid, Labour's Dame Margaret Hodge and Holocaust survivor Eva Clarke were among other speakers at the packed event on Tuesday night.
Karen Pollock, HET's chief executive, was loudly applauded for her introductory reamrks, in which she spoke of the need to continue to speak out loudly about the horrors of the Shoah.
Mr Javid, referring to this year’s Holocaust Memorial Day theme, “Torn From Home”, said: “As Home Secretary, I strive to make our homes a safe place… it is beyond tragic that such tragedies are still taking place in our world. It’s never been so important to learn the lessons of the Holocaust.”
Dame Margaret said: “I am a Jew and I am a proud Jew,” adding: “My determination to ensure that the Holocaust never happens again becomes stronger and stronger.”
Refecting on the rise of antisemitism in recent years, HET ambassador Ioana Diac said: “The only solution is education. We need to empower people to stand up for what it right, just and true.”
In a stirring speech, Ms Pollock urged the packed audience – which included Labour MPs Ian Austin, Jess Philips, and Dame Louise Ellman - not to be “bystanders”, adding: “we should be louder”.
Addressing fellow survivors including Zigi Shipper, Ben Helfgott and others, who were given an ovation by the rest of the audience, Eva Clarke recounted the story of her birth in Mauthausen concentration camp, Austria, on 29 April 1945. She and her mother were the only survivors of their family, 15 members of whom were killed in Auschwitz-Birkenau.
