Not since Alison's wedding has/had there been such a big family gathering.

[nohabloingleas]

This sentence is from an English grammar book "Grammar and Vocabulary for English Proficiency" exercise. The exercise is worded as follows: "Finish each of the following sentences in such a way that it is as similar as possible in meaning to the sentence before it". There is a starting word given.

The sentence that needs to be transformed is "It was the biggest family gathering since Allison's wedding"

I think that the correct transformation is "Not since Alison's wedding had there been such a family gathering", while the key states "Not since Alison's wedding has there been such a family gathering".

Am I wrong or has there been a mistake?

 

[Piscean]

Whatever 'it' is, it was in the past. Alison's wedding was before that. The past perfect is therefore appropriate.