Walking sticks

Please do not forget that the stick should be in the hand opposite to the painful joint. A painful left ankle would mean using the stick in the right hand.

Do not put too much weight on the stick because the rubber ferules slip on occasion.

Maybe a walker with a seat may also be an option?

There isn’t, apparently. The queen’s stick had been Prince Philips walking cane for stomping round the hills at Balmoral and presumably she didn’t want it to be cut down for her size.

It’s a good question. My experience is with adjustable trekking poles. These should be adjusted for length so that the arm is bent at a right angle. That means that if going downhill, the length of the pole needs to be longer and uphill shorter. I also use two poles, which effectively turn the walker into a more stable four-legged animal on uneven terrain.

Generally, the length of walking stick for someone with general infirmity would be the length from the floor to the prominent bone of the wrist when the arm is held straight and relaxed.

Hiking staves, shepherd’s crooks and so on tend to be longer, the tip of the stick held at sternum height with the arm bend into a V shape.

Perhaps the late Queen’s longer preferred style grew from walking her dogs on uneven terrain on Royal estates.

I use a higher stick when I have back pain reaching up to it makes me straighter but generally the correct height is as you say
I had to lower the height of my rollator as the higher setting was giving me shoulder pain
You can’t lean on your stick if it’s so high that your elbow is bent

It’s my understanding that the correct height is measured by a right angle at the elbow.
Two sticks are usually regarded better than one and certainly with two I walk straighter. Two are slightly more awkward shopping etc but if out on a proper walk I use two.
Not sure about the queen and why she used such a long stick.