TBH Llew, I thought the trailer ones were confusing, as there used to be differing limits for single and twin axle trailers (twin axles used to be able to do 70mph on the motorway) .
Yes, that may have thrown a few. Especially if, like myself, you haven't used trailers, and wouldn't normally be aware of the limits.
First car I drove as a learner, was my Dad's Singer Gazelle (7216 TE)
First time I drove was in a GPO Telephones company car - my Dad's, with me perched in front of him - when I was 12 years old. Off road naturally, on a then undeveloped unmade road in what was then a very new Harlow New Town, where my Dad was supervising telephone cable laying.