I'm going to be honest here, I wasn't even sure what marmalade was until a few moments ago. I had to Google it where I was given this description:
"Marmalade generally refers to a fruit preserve made from the juice and peel of citrus fruits boiled with sugar and water."
Upon reading that, I became even more confused as to why that would be the ideal snack before a long workout. If anything it seems like something you would eat before a nap, or after school as a young child because your mom wanted to shut you up with sugar.
I'm not a dietician though, so what do I know?
"The sandwich should be made with two 50g slices of white bread, 15g of butter and 30g of the bittersweet conserve for the perfect pre-workout fuel. She recommends eating one sandwich two to four hours before running or cycling to avoid indigestion and washing down the snack with a 200ml glass of smooth orange juice."
The reason being that:
"These carbohydrates are easily absorbed into the blood to provide a suitable energy boost."
Seems pretty doable and affordable too! Especially in comparison to all of the pre-workout crap that's marketed nowadays.