I wouldn't have thought it's particularly unusual to be unable to provide insurance details on the scene. Name and address is easy but not everyone carries their policy number around with them, and in the age of comparison websites I think you'd be surprised at the number of motorists who couldn't even tell you who their insurer is until they get home and dig out the documents.
It's irrelevant whether it's unsual or not. The law stipulates what must be done, just because you "don't have it on me" is not a legitimate excuse.
