In my own collection I have an example of a make do and mend jumper. I bought it about 25 years ago from a dealer in Brick Lane market, London. I think the yellow wool was previously a child's garment because it has a crinkled look to it, suggesting it has been unravelled and reused. On the inside of the jumper the wool has been joined in places which also suggests it was unravelled from a smaller garment. The 3 yellow buttons could have been used on a child's matinee jacket. The khaki green wool is a heavier weight and may have been surplus army supplies. It's really beautifully made and whoever made it took great pride in their work even though they had to 'make do'.
For fans of forties fashion there is one book that's a must have, I cannot recommend it highly enough!