By the break, Tonga had another man in the bin, lock Harison Mataele getting pinged for offside while Scotland were hammering at the line to no avail.
And early in the half the visitors dropped to 13 men when Taniela Filimone was done. Still Scotland toiled to break what was a resolute visiting defence.
Scottish possession was huge. Scottish errors were troublingly high.
There was yet another yellow for Tonga – a deliberate knock-on by centre Fine Inisi – just short of the hour.
Finally, Scotland made them pay. Off a line-out, Van der Merwe galloped through a gap and nobody was stopping him. Burke added another conversion and it was 28-0.
Still down to 14, Tonga were done again when a rolling maul saw Ashman go over. Burke did the job with the extras once more.
Tonga were easy meat to a Scotland that were now full of running.
Four minutes after Ashman scored, substitute Horne got the sixth, a slick move that began in earnest when Smith flung a sweet long pass left to right to Kyle Steyn. Kyle Rowe arrived in support and Horne was on his shoulder. Much more like it.
Horne converted his own try to make it 42-0, then scored his second after excellent work from Ritchie. The half-century was brought in minutes from the end when Ashman crashed over again. Horne’s sure boot made it a 56-point tally.
It was the second game of the autumn where Scotland kept their opponents scoreless – they did it to the USA as well – but this series will not be remembered for the landslide wins rather than the ones that got away.
