The former editor of Waitrose Food Magazine says he received death threats after jokes he made about killing vegans were shared in the media.
In response, Sitwell wrote: "Thanks for this. How about a series on killing vegans, one by one. Ways to trap them? How to interrogate them properly? Expose their hypocrisy? Force-feed them meat? Make them eat steak and drink red wine?"
After the jokes were made public, Sitwell resigned from his position, with Waitrose saying it was 'the right and proper move'.
The supermarket also said: "Even though this was a private email William's gone too far and his words are extremely inappropriate, insensitive and absolutely do not represent our views."
The story made headlines across the media, with Sitwell and the vegan journalist - Selene Nelson - both attracting attention on social media.
The pair met on The One Show last night to talk about the experience - with both revealing they had received death threats and other abuse as a result of the incident.
Sitwell said commentators wrote to him 'wishing the death of my child' and 'the rape of my wife'.
"I got a reaction very similar, got people wishing death on me… people constantly sending me meat gifts as if that's going to shock me," added Nelson, who said she was sorry Sitwell lost his job.