A "peaceful" vegan activist was imprisoned for gun crime and told farmers to kill themselves, The Daily Telegraph can reveal as he prepares for his biggest day of protests.

Joey Carbstrong, who has more than 50,000 followers on social media and has become the face of the movement in recent weeks, also compared farmers to Hitler and said that what worked in stopping the Nazis "was tactical violence".

After hitting the headlines when he confronted Jeremy Vine over a ham sandwich, Carbstrong took to daytime television to publicly condemn "any death threats and any name calling", saying he practises "peaceful, non-violent advocacy" and insisting "I do not hate farmers".

But as he is adopted as the unofficial spokesman for vegans across the country, The Daily Telegraph can reveal that in the past he had used a very different approach in which he said dairy farmers were "worse than Nazi Germany" and that the "non-existence" of people who eat fish "would benefit the planet".

The Australian, whose real name is Joseph Armstrong, openly admits that he has a very colourful past and was involved in drugs and violence before converting to veganism during a spell in prison.

After leaving school early he quickly developed a heavy drug addiction, starting with cannabis at the age of 14 and then turning to alcohol and methamphetamine at 15, ecstasy and hallucinogens at 16, and then heroin, cocaine and benzodiazepines.