But seeing him in his office-cum-editing suite, the reason is obvious. Every available inch of wall space behind his desk is covered with awards for his documentaries made over the past 27 years. There is recognition from the British Academy, and Broadcasting Press Guild, and nominations for the Prix Italia.
Despite all these plaudits, Bloomstein is as down to earth as they come. Like Harold Pinter and Arnold Wesker, he grew up poor and Jewish in Hackney. With a father who came from Poland and a mother of Russian origin, he was aware at an early age of "the potential dangers of being an outsider" and "the sense of poverty and incipient racism which, as for all members of minority groups, brought home the fragility of my position".
Early exposure to television documentaries gave him the urge to become a film-maker. He made his first documentary, at the age of 30, for the BBC in 1970. That project, a series of verite studies of British life entitled All in a Day, was the beginning of a prodigious body of work. This includes Martin Luther King - the Legacy for Thames TV on the 20th anniversary of King's assassination; The Longest Hatred, a trilogy charting the history of anti-Semitism; the Prisoners of Conscience series for the BBC; and Human Rights, Human Wrongs, the BBC series soon to mark its 10th anniversary.
Human rights and civil liberties are a continuing thread and driving force in his work. So, too, is enduring interest in the Holocaust. Lessons of the Holocaust is his first educational film and he's genuinely happy to have done it. "The media have an important role to play in education," he says. "You have to grasp the potentialities and think of education not as a ghetto area but as a place where films can provoke ideas, discussion, even change."