Past perfect or simple past with 'ago'?

Question

As a non-native speaker but a teacher of the English language I've come across the following question reading a pupil's report: Should she use the simple past or past perfect in her sentence?

Last week we came back from a class trip to New York. We planned (OR) had planned that trip half a year ago.
_{(meaning: half a year before NOW)}

Although we teach that ago is a signal word for simple past, I would go for past perfect here, since the action of the second sentence clearly takes place before the first one and before the rest of what the report is about (the class trip itself).

How would a native speaker put it?

Answer 1

In general I agree that using ago implies that the simple past would work better. In this case, however, the simple past doesn't provide the obvious and relevant connection/link between the two sentences that had planned offers.

If it were me, I would use had planned (for its link to the previous sentence) but replace ago with prior to avoid any subtle semantic imperfections. (Edit: Except you stated that the semantic intent was half a year before "now"... So this suggestion is less useful.)

With that said, neither example is particularly offensive, and I doubt that other native English speakers would have strong opinions either way if they encountered either example in real life.

Answer 2

Native [British English] speaker here. I would never use 'ago' with the past perfect as it is relative to the present, not the past. As has been mentioned, you should use 'prior' or 'before' (or 'preceding' if you prefer something more formal) to indicate a point or amount of time before a time in the past.