Among other things, he has compared "Zionists" to Nazis and written that "Jews" should reflect on the actions of the Israeli military. He has described Labour Friends of Israel as "A party within a party" and, after calling Dame Louise Ellman a "Vile Zionist", he wrote: "Is it time for a human being to stand against Louise Ellman in next year’s general election." In a message sent to Luciana Berger, the former Liverpool Wavertree MP, after she highlighted the rising problem with food banks under the government in 2012, he wrote: "What about the Palestinians?"
Some of his messages appear to be a clear breach of the internationally accepted IHRA definition of antisemitism. The examples cited by IHRA include: "Drawing comparisons of contemporary Israeli policy to that of the Nazis" and "Holding Jews collectively responsible for actions of the state of Israel."
Following our expose, Conservative Friends of Israel wrote a measured letter to Fran Unsworth, the BBC's head of news, pointing this out and asking her to consider if she felt it appropriate to carry on using Prof Ashton.
I did not for a moment imagine that Ms Unsworth would send a satisfactory response. I assumed that her reply would be defensive. But what I did not expect was the response she did send.
It is a response so breathtaking - and genuinely shocking - that I wonder how she can in all decency continue in her post, given what it reveals about her mindset.
Most of the letter is blather. She points out, quite rightly, that "Professor Ashton was eminently well qualified to speak about this subject [public health]. He has held positions at various universities, and was regional director of Public Health for Cumbria. More recently, he was president of the Faculty of Public Health." (Although she fails to point out that he had to take a voluntary leave of absence from the Faculty of Public Health after calling one e-cigarette advocate a "c**t" and another an "onanist".)
But Prof Ashton's qualifications as an expert are not the issue. The issue is that he has - repeatedly, over many years - made remarks which the under the IHRA definition are antisemitic.
And what is her response to that?
"I quite understand your strength of feeling about the views you have ascribed to Professor Ashton on Israel and Zionism...Professor Ashton did not, of course, make any comments of the kind that you describe in this programme and I hope you understand that I would have grave doubts about the impact on freedom of speech, and the BBC’s ability to report freely and impartially, if we were to ban contributors from speaking on the subject of their acknowledged expertise because of the political views they have expressed, however abhorrent some members of the audience may find them."
I keep reading those words and every time I do I find them no less staggering.
Ms Ashton refers to remarks which are, I repeat, prima facie antisemitic as being "political views" which "some members of the audience" may find abhorrent.
Antisemitic remarks, according to the BBC's head of news, are merely "political views". Yeah, some people won't like them but, heh, others will and it's not our job to take sides in the day-to-day cut and thrust of political views, you know. Antisemitism - it's just a political choice.
The charitable explanation is that Ms Unsworth is an idiot, who does not really understand the meaning of words and has no conception of what she is saying when she defends such views as merely poliical.
But I doubt very much she is an idiot. The real worry is that she knows exactly what the words she used mean and she genuinely does think that, when one of the BBC's regular talking heads is exposed for having having such spouted such sentiments, he is merely expressing a political view.