Dear Carol
Im afraid I made a mistake in my recent reply by saying William Armstrong married Margaret Kilgour. It was in fact Mary Jane Kilgour and they had a daughter Margaret after their marriage in 1924. I cannot find her birth date but she attended Douglas School of Art.
I have also found a census record in 1911 in Yorkshire where a William Armstrong (correct age) was living at Low Farm, Towthorpe, Yorkshire with his sister Elsie (correct age). He put himself down as single and Farmer's son Manager. She was single, Farmer's daughter housekeeper. All these facts fit our William and Elsie but cannot prove that it is actually them. I suppose it is possible that he went back to Yorkshire for a short time to help out a farmer friend of his father, Samuel Wilson Armstrong. Who knows!
Doreen