It would be helpful to know more clearly what you mean by "English" and what you mean by "primary school." By "English," do you mainly mean literature, grammar, spelling, composition, or all these. By "primary school," are you focusing on a particular age or grade level. Knowing what you have in mind here will allow us to give you better-informed responses. Thanks!
This is a very difficult question to answer, because not all teachers are alike. As with any profession, there are good and bad teachers. So generalizations can be made only with great difficulty. In addition, with teaching, it is always a two way street. Students have to be willing to learn. In part this is a parent's responsibility to model responsible behavior and inculcate to their children that learning is of utmost importance.
With these things being said, I will hazard to make one generalization. I believe that the study of English has taken a step back, because the American curiculum does not emphasize the classics as much. I believe that the study of Latin is still very important in the study of English. For example, in the past English grammar was learned through a study of Latin. Moreover, some of the greatest works of the western canon are written in Latin. Hence, the study of Latin and the works in Latin is a great boon to the study of English.