None of them was, or none of them were?

Which is the correct grammar: none of them was, or none of them were? Should the agreement be with the singular “none” or the plural noun?

Yes, it is a tricky one. I believe it is because the appearance of singular and plural in the sentence causes confusion as to where the agreement should be. I have seen and heard plenty of cases where it has tripped people up. On the Internet I have found grammar articles devoted to it and forum posts where people ask the same question.  

The answer is: Agreement is with the noun in the sentence and not with the “none”. If the noun is plural, the agreement is plural. But if the noun is singular, the agreement is singular.

For example:

None of the pies were eaten because there had been a food contamination warning.

Not: None of the pies was eaten because there had been a food contamination warning.

However, if you are talking about one item, agreement is singular.

For example: none of the pie was eaten.