1888
The name has changed over the years (locomotive duty, road fund duty, vehicle excise duty, etc) but it's essentially the same thing, a tax you have to pay to use a motor vehicle on the road.
You get people in cars that see a red mist and think its okay to try and kill you or injure you for holding them up for 10 seconds..
What they should've done is stayed on the correct side of the road and waited for the oncoming vehicle to pass. I don't believe that they just rode on the wrong side of the road the whole way.
As i have said before.
It isn't just 10 seconds is it.
If you are "Tail end Charlie" in a rolling roadblock of a dozen or more vehicles, it can easily end up being several minutes if overtaking opertunities are limited on a busy road.
That is why some drivers get mad.
I don't believe it either, it's far more likely that they were riding on the pavement and then moved out onto the wrong side of the road due to the van, just as the OP explained. The fact that the OP saw them them move back onto the pavement after the junction adds more credibility to this.