Soldato
I went with my friend who's bought loads of cars and the first thing he said when he saw the log book was that it ain't registered as a Cat so I took that for it. Seller also agreed with this.
Unfortunately, the only time you'll find a category listed on a V5C is if the car was Cat C (or worse) and needed a VIC. Cat D is not recorded on the V5C, neither is the newer classification of Cat N (in my understanding). Cat S will be mentioned in the additional notes section, though, as was the case with Cat C/B cars, etc.
A history check should tell you the last change of owner but it's probably the case that it's now down as when you got it, not the previous keeper. Might be worth speaking to someone about that, though.