I was brought up in Glasgow and always knit with my left needle under my arm. My mother was from the NE of England, just to complicate things, and she taught me to knit. To me, the way of knitting with both needles held in front of your body looks awkward, but it seems to work.
Shrub suggests circular needles, and that would certainly make sitting in your chair easier. I use them a lot, as I hate sewing up, and they are just as good for flat knitting as for circular, if that makes sense. I sometimes do as Alegrias2 does too, and sit squint if I'm on a difficult chair.
Was your great grandma from Shetland, Alegrias2? I believe that they would walk along knitting while carrying the peats home (and no doubt the baby too), as they had to make full use of time when the knitting was a way of earning money.