Question

why did the British preserve official documents​

Answer 1

Answer:

The British believed that by preserving official documents it would be easier for them or any other persons to know about the decisions taken in the past.

Answer 2

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British had preserved official documents, because they thought if they write and record everything, it will later be easier for them to study them and debate. They kept official records of what they thought was right, so that in the future, those records can serve as proofs of all the decisions that they had taken.