From Longman Dictionary of Contemporary Englishhead girlˌhead ˈgirl noun [countable] SESthe girl who is chosen in a British school each year to represent the school
Examples from the Corpus
head girl• By all accounts Selina was a bright child who ended up as head girl of her secondary school in Guisborough near Middlesbrough.• I was made head girl there and captain of the senior hockey team. 