David –
You believe correctly! When clearing our parents’ home I found a part-used jar of that ‘Screwfix’ material in the garage. Suspecting asbestos, I added some water, mixed it with a stick and let it set hard.
It was on the same shelf as the toffee-tin containing assorted Rawl-drill “jumpers”, fibre plugs and screw-diameter gauge. (Our Dad, a scientist by profession, was very practical with building-related work, and to a very high standard.)
….
Breast-drills: mine stands at the back of the bench, ready for duty though I admit not using it very often. Sometimes I used a countersink bit with it for deburring power-drilled holes in steel. I’ve pondered making a stand for it, turning it into a small-scale version of the old manual drilling-machines, but I’ve enough to do as it is! Though at least I could use it indoors when the workshop is too cold to inhabit.
I’ve a couple of carpenter’s braces too, and a few bits, but have used those only very rarely.