On this website http://www.emaths.co.uk/KS2SAT.htm#English
they have the marking schemes which are more useful than the actual papers IMO. They tell you the differences for instance between a 1, 2 or 3 mark answer with examples. The higher marks are gained by referring to language used in the text.
DS has great trouble doing this more advanced style of answer where you need to say how someone felt & give references. We are going to work through them together so he can get the idea & also I ask him about things we see on tv - why do you think they did that, what would you do, how would you feel in that situation etc.