Edukator, if you’re trundling along at the speed limit (where appropriate), the only reason to overtake you is if the overtaking driver is either:
a) looking to improve their view of the approaching road*
b) a knob
* I can understand why driving behind a van can be difficult or frustrating. They have the performance of an average car but can be like driving behind a wall that obscures visibility. Simple solution is for the following driver to drop back.
If you’re hovering around 55mph, I would overtake (if safe) and continue at 60 (in NSL area, obviously). If you’re hovering around 60 and I’m in the car, I’ll drop back; if I’m on the bike, I’ll overtake to improve my visibility along the road.