The taughtline hitch is a much better knot for this.
I never could master the trucker's hitch[1] though :-)
[1] https://en.wikipedia.org/wiki/Granny_knot [2] https://www.fieggen.com/shoelace/grannyknot.htm
L over R, L over R would make a granny knot.
But maybe in the UK both are called a granny knot?
Interestingly, when a granny knot is collapsed (the cord on one side gets pulled taut), it becomes two half hitches. When a square knot is collapsed, it becomes a larks head or cow hitch knot. In the balanced state, the granny is a weaker knot and the square is stronger. In the collapsed state (then cleaned up a little bit), two half hitches is a stronger knot than a cow hitch.
Same in the UK.
Also, it's a taut-line hitch:
https://en.wikipedia.org/wiki/Taut-line_hitch
taut, meaning tight, not taught, the past tense of teach.