As I know, English has been taught in Chinese schools since the early 20th century. Most of those teachers were missionaries from Great Britain and the U.S.A.. My father who used to be a university professor of English began to be interested in English by the inspiration of an American priest who was propagating Christian mission in his village. He loved English so much， kept learning English and graduated in English department of Zhejiang University in 1947, when few Chinese people obtained such education. Latter, many Chinese scholars like my father , even me , have been contributing their whole lives to the career of teaching English by translating English teaching theories and methods and training Chinese students in a bilingual way , which makes them more easily to learn.
But if you need to grasp a purer foreign language , you should learn from those who are well educated native language speakers. In fact, it is apparently far from satisfaction for most of the Chinese teachers of English who have been learning English from books not from the true life. Then from the early 1980s, as the carrying out of the Chinese open-door policy , more and more native English teachers taught English in China. At that time , English teachers were so needed that even an English speaking house wife could stand in front of a Chinese class to just simply tell something about her native culture and folks. They did not even need to speak a single Chinese. However, I had a better chance to learn from some American professors in the education college.
Now , things have changed a lot , those who are allowed to teach English in Chinese school should , of course , be well educated in English language with proper degrees and credentials ( but not necessary to speak a single Chinese word ). At the same time , more and more Chinese teachers of English have chances to go abroad to study English. It is true that as the increase of communication , Chinese people have much better chances to learn much better English.