I have an old stamp that saysTOP: Cape of good hope : the bottom says : Postage one penny: its red ANY VALUE?

Answer 1

check the Scotts Postage Stamp guide, they have an international version

it is from South Africa

Answer 2

I don't know, but keep in mind that a one-penny stamp doesn't necessarily mean it dates back to when it cost a penny to mail a stamp.

For many years (even now, I guess) there have been penny stamps so that if something was a certain amount of postage, pennies could be added on to make the full postage. You still see it when stamp prices go up, the post office often would do penny stamps so you could make up the difference.