A UKIP member who said he looked after party leader Gerard Batten at a rally called for a campaigner to be beheaded, a BBC investigation has found.
Kenneth Allen said Gina Miller, who campaigned for MPs to vote on Article 50, should have her head cut off and left outside Buckingham Palace.
He also said a “full pig” should have been thrown at a mosque in Blackpool.
Mr Batten said he “deplored” the posts and Mr Allen was not a member when he made the remarks on Facebook in 2016.
Mr Allen also warned a woman before the EU referendum to “do yourself a big favour and vote out so you don’t get raped of (sic) a migrant”.
He said he looked after Mr Batten when the UKIP leader appeared at a rally in Sunderland in September.
Mr Allen also called Ms Miller a “cow traitor” in the Facebook post.
He did not want to comment when he was approached by BBC Inside Out.
Ms Miller said: “It’s frightening. To actually be confronted with the words.
“It’s ridiculous to think that I now think it’s normal for people to threaten me on a daily basis, but to see it in black and white… that somebody wants me to be beheaded and my head put outside Buckingham Palace.
“This is just one of the death threats I get almost on a daily basis.”
UKIP leader Mr Batten said: “I attended a rally organised by justice for women and children on 15 September.
“Many people ask to have their photograph taken with me at these events and it would be impractical and rude of me to refuse them.
“Kenneth Allen was a lapsed member who renewed his membership in April 2018. When he made the posting in question he was not a member of the party.
“I deplore the remarks made and these in no way represent the views of me, UKIP, or the overwhelming numbers of our membership.”
He said the party could only take action if someone lodged a formal complaint, and he hoped the BBC would not try to smear UKIP or himself by means of “guilt by association”.
You can see more on this story on Inside Out on BBC One in the North East and Cumbria at 19:30 GMT on Monday 21 January or afterwards on the iPlayer.