Spiral staircases were a clever defence in medieval castles. They were almost always built with the spiral in the same direction (clockwise, when looking up from the bottom) so that the defending swordsman, who would either be coming down the stairs or backing up in reverse, could freely swing his sword. Conversely, the attacking swordsman (ascending the stairs) would have his swing blocked by the wall.

This, of course, assumed that both attacker an defender were right-handed, which most were.

Left-handed swordsman, though rare, had the advantage of surprise when attacking out-in-the-open – they had fought (and trained against) more right-handed opponents than their adversary had fought left-handed opponents. Their attack when ascending standard spiral staircases was also not blocked by the wall.

The warlike Clan Kerr trained to use their weapons with their left hands. Scottish Poet James Hogg (1770-1835) wrote, in The Raid of the Kerrs:

But the Kerrs were aye the deadliest foes
That e’er to Englishmen were known
For they were all bred left handed men
And fence [defence] against them there was none

and Walter Laidlaw wrote, in The Reprisal:

So well the Kerrs their left-hands ply
The dead and dying round them lie

Legend has it that, to allow them to more easily defend Ferniehirst Castle – seat of the Clan Kerr – the staircase was built spiralling in the other direction (see illustration above, with left-handed Kerr shown with ginger hair).

Is this true? Certainly, the castle does feature a reverse spiral staircase, but a 1993 study found no increased incidence of left-handedness in Kerrs.

Personally, I don’t Kerr whether it’s true or not – it’s a great story.