If it says Station Wagon on the V5, it was originally a Station Wagon, with seats in the back.
If it says Light Utility 4x4, it was originally a hard top, or a truck cab, but has been "Station Wagonised" by a previous owner.
Also, to make your research easier, that isn't a Defender, it is a Land Rover Ninety. But most vehicles of that age will have had bits of later models added at times in their life.
When you say "bench seats", I assume you mean seats on the wheelboxes, facing into the vehicle?