More and more young people are being drawn into the world of violent extremism, a senior police officer has warned after a young neo-Nazi caught in an undercover MI5 sting was convicted of planning a mass gun attack. Alfie Coleman, a former supermarket worker from Great Notley in Essex, compiled a hate-list of colleagues and customers he branded with racial slurs or as “race traitors”. He wrote a “manifesto” in a diary and identified potential targets, including the “lord mayor of London” and a mosque. The 21-year-old was found guilty of preparing for terrorist acts on Thursday after an Old Bailey retrial. From the age of 14, Coleman had begun to trawl the internet for extreme rightwing material, including a neo-Nazi text he downloaded on his iPad. He was caught after undercover officers from MI5 engaged with him in encrypted chat as he sought to buy weapons.…