LONDON (Reuters) -British newspaper publishers could be shunned by investors because they do not offer decent returns, threatening the future of a pillar of democracy, a government report said on Friday. Britain’s major newspapers, which include The Sun, Daily Mail, Sunday Times and Daily Telegraph, have seen circulations decline sharply in the last couple of decades, although they have countered this to some extent with online products. “We have found a clear pattern of declining sustainability in the sector since 2010, which is consistent with reduced income and costs, as well as a reduction…