This is a bit of a vexed question. Some people insist that collective nouns should always take a singular verb; others are adamant that they should take plural verbs.
Whatever you decide to do after reading this post, it’s up to you. But one thing I would suggest—if you’re writing on behalf of an organisation, check their style guide. If their style guide doesn’t address the issue, come up with a decision and ask them to document it in their style guide. (If they don’t have a style guide, recommend they create one.)
What is a collective noun?
Before we go any further, what is a collective noun? Collective nouns, according to Mark Tredinnick in The Little Green Grammar Book are nouns which, ‘though singular themselves, refer to notional or real gatherings of people, other animals, plants, works or ideas’. Some examples are:
A Mob of Roos
And of course there are many others.
What the experts say
Now Mark Tredinnick is a firm believer in collective nouns taking singular verbs. But there are other views on this. Michael Swan, in Practical English Usage suggests that either singular or plural can be used, although if we are using singular determiners (a/an, each, every, this, that) it’s best to use a singular verb.
Are you confused yet?
To add to the confusion, the BBC has different policies on singular or plural verbs with collective nouns, depending on which department is using it.
BBC Radio News says they are plural (The Government have introduced a bill…), and BBC Online likes them to be singular (The Government as introduced a bill…). BBC Television News doesn’t have a policy! They use whichever they think sounds best ‘in the context’.
My view, for what it’s worth
To throw in my two cents worth, I say use whichever version you like. But be consistent.
If you are always going to use singular verbs, always use them. If plural, always plural. And if you are going to mix them up like BBC TV News, be consistent within each sentence. So to quote their example of what NOT to do:
The jury was out for three hours, before they reached their verdict.
It should, of course, be:
The jury was out for three hours, before it reached its verdict.
Be consistent and put it in the style guide.