English Grammar Explanations - Past perfect
esl.fis.edu/grammar/rules/pastperf.htmThe past perfect tense is used in unreal or hypothetical stituations, as in the following sentences: If I had known you were in Frankfurt, I would have called you. ( but I didn't know you were here so I didn't call you!) If I had had enough money, I would have bought you a better present. ( but I didn't have enough money.)