Collective Nouns

I saw these enjoyable examples of collective nouns with plural verbs in England:

We are an agency that become excitable when... (an ad for an advertising agency)

When England win, you win.... (a billboard ad for some kind of deal whereby when England would win a game in the World Cup, you'd win a ...?)

So what is the deal with collective nouns and plural verbs? Why do these sound so wrong to us, yet, find their way past proofreaders and editors in the UK?

In North American we tend to use a singular verb with collective nouns. We would write, “The school board says...” or “Parliament is sitting.” However in England the preference is to use plural verbs, as in the examples above.

Alan Garner is, as always, pithy on this subject:

The main consideration in handling [collective nouns] skillfuly is consistency in the use of a singlular or plural verb. If, in the beginning of an essay, the phrasing is the faculty was, then every reference to faculty as a noun should be singluar throughout the whole. On the other hand, a writer who wishes to emphasize the individual persons more than the body of persons may decide to write the faculty were, although members of the faculty were is prefereable because it's more accurate. [A Dictionary of Modern American Usage, p. 133]