for being 1st in class for/in English.

English is the name of a class in most English-speaking schools I know of. It's where you learn grammar and reading and writing skills. Smith was among the top students in that class. I'd use "in".

English is the name of a class in most English-speaking schools I know of. It's where you learn grammar and reading and writing skills. Similarly, you might have classes called "French" or "Spanish" or "World History". Smith was among the top students in that class. I'd use "in".

But English school systems and other ex-British school systems may do it differently. PGWOdehouse was always awarding his fictional students prizes in things like "Scriptural Knowldege", and "class" can also mean "all the students in a particular year of school", so Smith could have done the best at studying English amont all the 8-year-olds.

In the UK we would generally say "Frank was first in his class in history" if we are talking about a position in a list or ranking. However when taling about the individual alone we might use "at" - Frank was good at fencing or French.

This certificate is awarded to Johnson Smith of Primary 3A for coming first in English.