This is an old article, but according to Dr. Bernard Lamb, a reader in genetics at Imperial College London (thisislondon.co.uk), undergraduate students from Singapore and Brunei, whose second language is English, have a better command of English than do their native-speaking British counterparts.

Dr Lamb said: "All these students have good or excellent A-levels or their equivalents.

"The overseas students were generally less bad and the worst were UK raised and usually of British ancestry.

"There was little evidence of students being taught the relevant rules at school, or of the students having been corrected for obvious and frequent errors. Many did not even regard these errors as important.

"The Government and the educational establishment need to be shaken out of their current complacency about standards of English by constant exposure to evidence such as that presented here from intelligent and highly-qualified undergraduates."

Most of the errors are apparently due to spelling or punctuation:

Two of the "vocabulary" errors in the chart are really spelling errors, as are the the incorrect plurals, thus giving us 10 spelling errors and 1 punctuation error, 11 out of 14, almost 80% of the errors noted. And if you consider the "clumsy" writing as perhaps someone disliking split infinitives, then, that's not really clumsy nor an error. In fact, the article gives a long list of spelling errors, making spelling the culprit in bad English. (For more details, see Lamb's article Cows Inseminated by SeamanErrors in the English of Highly Selected Undergraduates.) Although the spelling errors are rather glaring, how did spelling (and punctuation) come to equal a command of English?