During my MSc in the late 1970s, I had a sweet-natured chum who belonged to Militant, so I observed them for a full year.
They were boringly ernest, utopian, sometimes hectoring, but not sinister. Never heard anti-semitism, or any wish to abolish Israel then.
In the early 1980s, Michael Foot & Tony Benn had what were considered far left policies, but I think they would have booted out anyone spouting anti-semitic crap.
Livingstone was always of the extreme batshit far left, always deliberately provocative and offensive.
However, I didn't notice any anti-semitic remarks before his 2nd term as Mayor in 2004, when I suspect he suddenly noticed the size of the Muslim vote and had no scruples about maximising it.
In contrast, Sadiq Khan backs a Tel Aviv festival in London and publicly condemns antisemitism.
imo, he appeals to people's better instincts, whereas Livingstone stirs up age-old prejudice of the worst kind.
Great interview in the Jewish Chronicle, very encouraging:
www.thejc.com/news/uk-news/145335/interview-sadiq-khan-believe-me-i-wont-be-another-ken-livingstone
"“We have a huge amount in common."
"I’m completely comfortable in a synagogue, you’re perfectly comfortable with me, even though we’re of different faiths."