Fair point Varche - must admit I was just thinking of nearly identical 56mph limiters failing to pass each other for miles on end, which can cause serious congestion with dangerous tail-backs particularly on two-lane stretches. A bit of consideration from the truckers wouldn't go amiss here.
I don't drive HGV either but I have spent a fair bit of time as a passenger and, as you say, it has been useful experience. I was amazed at what a PITA it is when erratic speed from a car in front causes a truck to lose momentum which can take ages to build back up. It has certainly helped my awareness of HGV blind spots, turning space and so on. Getting knocked off my bike (years ago) by someone with a 360 degree blind spot was also a wake-up call.
The mainland European habit of keeping your indicator on throughout an overtake isn't a bad idea - an acknowledgement that you are in the outside lane temporarily for the duration of the overtake rather than living there permanently just because you drive an Audi.
Anyway - I stick to my initial point. Starting an overtake that is unlikely to complete this century because you are both on the
same limiter should be discouraged Libyan style.