As I was learning the Queen's english as a boy in Canada, I learned that the verb must reflect the singular or plural nature of the subject, such as "The boy is going to school", not "The boy are going to school". This also applied to a singular subject which included more than one person or object, such as "The team is going to play tonight", not "The team are going to play tonight".
Now that I have this firmly embedded in my mind, I see that the British have changed this for some unknown reason. Now it is "The team are playing tonight", even though "team" is singular.
I realize that language is fluid and ever-changing with the times, but this example seems to violate a "law" of grammar. How did this change happen? Is it engraved in stone somewhere?