Singular And Plural Verbs
From 'Grammar' part of The ABC Of Plain Words by Sir E Gowers (1951)

The rule that a singular subject requires a singular verb, and a plural subject a plural verb, is an easy one to remember and generally to observe. But it has its incidental difficulties.

(i) Collective words.
About collective nouns, or nouns of multitude (Department, Parliament, Government, committee, and the like), see Collective Words.

(ii) Words linked by and.
To the elementary rule that two singular nouns linked by and should be given a plural verb justifiable exceptions can be found where the linked words form a single idea. The stock example is Kipling's "The tumult and the shouting dies"; "the tumult and the shouting", it is explained, are equivalent to "the tumultuous shouting".

Perhaps these official examples might be justified in the same way:

Duration and charge was advised at the conclusion of the call.
Your desire and need for a telephone service is fully appreciated.

It might be argued that "duration and charge" was equivalent to "the appropriate charge for that duration", and that "your desire and need" was equivalent to "the desire arising from your need". But it is safer to observe the rule, and to leave these questionable experiments to the poets.

Other instances of singular verbs with subjects linked by and cannot be so easily explained away. They are frequent when the verb comes first. Shakespeare has them ("Is Bushy, Green and the Earl of Wiltshire dead? ") and so have the translators of the Bible ("Thine is the kingdom, the power and the glory"). If we may never attribute mere carelessness to great writers, we must explain these by saying that the singular verb is mor e vivid, and should be understood as repeated with each noun —" Is Bushy, (is) Green, and (is) the Earl of Wiltshire dead? " Those who like to have everything tidy may get some satisfaction from this, but the writer of official English should forget about these refinements. He should stick to the simple rule. See also There Is.

(iii) Words linked by with.
If the subject is singular the verb should he singular. "The Secretary of State together with the Under Secretary is coming", not "are coming".

(iv) Alternative subjects.
If both are singular the verb is singular, and if both are plural the verb is plural.

Either the Secretary of State or the Under Secretary is coming.
Either the Ministers or their officials are coming.

If one is singular and the other plural the verb usually takes the number of the one nearest it ("either the Minister or his officials are coming"), but if we want to be scrupulously logical we must have two verbs and write:

Either the Minister is coming or his officials are.

(v) Attraction.
The verb must agree with the subject, and not allow itself to be attracted into the number of the complement. Modern grammarians will not pass "the wages of sin is death". The safe rule for the ordinary writer in sentences such as this is to regard what precedes the verb as the subject and what follows it as the complement, and so to write "the wages of sin are death" and "death is the wages of sin".

A verb some way from its subject is sometimes lured away from its proper number by a noun closer to it, as in:

We regret that assurances given us twelve months ago that a sufficient supply of suitable local labour would be available to meet our requirements has not been fulfilled.
The Minister's views in general . . . and the nature and scope of the information which he felt would assist him . . , was indicated at a meeting. . . ,

Sometimes the weight of a plural pushes the verb into the wrong number, even though they are not next to one another:

Thousands of pounds' worth of damage have been done to the apple crop.

In these sentences has, was, and have are blunders. So is the common attraction of the verb into the plural when the subject is either or neither in such sentences as "Neither of the questions have been answered" or "Either of the questions were embarrassing". But in one or two exceptional instances the force of this attraction has conquered the grammarians. With the phrase more than one the pull of one is so strong that the singular is always used (e.g. "more than one question was asked"), and owing to the pull of the plural in such a sentence as "none of the questions were answered" none has come to be used indifferently with a singular or a plural verb.