Which pronoun should be used to refer to, say, an orchestra? Does it go on concert tours, or do they?
Intuitively I’d go for “they”, but intuition is known to fail…
The orchestra goes on tour. The members of the orchestra go with it.
Strictly speaking the correct pronoun is it but as it is often the case that we are referring to members of the orchestra, the comfortable pronoun can be they. It is, therefore, a matter of context and preference.
For collective nouns, the agreement of the verb with the noun dictates that we use singular.
Concretely, whenever we refer to a group, we are referring to one single entity as a whole, and thus we use singular counts for the group.
E.g. The herd of sheep is running amok. This follows from the fact that we are referring to the herd as a whole and as one entity rather than to all the individual sheep.
Thus, it will be the right usage.
P.S. When it come to the difference between american and british english, I have learned from Wren and Martin, which predominantly teaches in the British style and they used singulars there for collective nouns.