Democracy cannot be imposed successfully. Just as we as human beings have choices, so do countries and just as the path and pace of learning for each of us is unique to each of us individually - and resulting from those choices - so too is it for China.
While we may not like what China does by way of human rights, fairness and respect, judging her and expressing that judgment helps neither her not ourselves. Who are we to judge anybody? Are we perfect? Is the record of western “democracies” perfect also? No.
Change comes best through observation of example and experience, and a desire, willingness to adapt as a result of seeing the benefits of another way of being and doing. The sooner western nations can prove through good practice that precepts like kindness, acceptance and harmlessness really work, the sooner others will begin to adopt them - even the politicians of China, or Burma. Having a bad record does not mean it cannot be improved.
I believe that David Cameron was right today to remind his Chinese audience about how democracy works in the UK, without hectoring. It is their right to decide what to do about their way of governing - however distressing some of their actions may be to the hearts and minds of others watching, or those who have chosen, nobly, to be a part of this opportunity for change as protagonist and teacher.