A very good standby.
Mamade is the fallback when you have no seville oranges, and is a reasonable alternative - though sweeter. The thick cut is my favourite. However, if only thincut is available I add thin sliced citrus peel pre simmered until tender and use the juice with the water to be added. I also put in a teaspoonful of powdered ginger and a good slosh of lemon juice which gives it more tang. Beet sugar is not as good as cane sugar because the marmalade seems to discolour very quickly. It is ready after 15 minutes if you get a good rolling boil on it.