Local authorities say he died from natural causes – but his mother has told reporters she has doubts over the verdict.

Vanessa Bates, an English teacher, said: "He was making a name for himself in the world of conspiracy theorists and had been invited to speak at a conference in Poland in July.

"He was staying with a woman who he had not known for long and she told me how she found him dead on the sofa.

"But I think Max had been digging in some dark places and I fear that somebody wanted him dead."