Jaffa cakes are 50% sugar, but what’s in the other half?

Ever since hearing that the England football team takes Jaffa cakes when it goes on tour, I've looked at them with fresh eyes. What is it about the spongy treat that makes it so popular? If athletes eat them, does that mean they qualify as a healthy option?
Jaffa cakes were first made by McVitie's and Price in the UK in 1927. The original was a little sponge topped with jam and a layer of chocolate. There is quite a lot more in there now however. There are also a lot more brands, though the distinction between them seems to be on price and marketing, rather than recipe, with own-brand Jaffa cakes from Jacob's, Aldi, Lidl, Centra, Supervalu and Dunnes, for example.
So what's the difference?
McVitie's wins on marketing. The packaging even mentions its Jaffa cake Facebook page, which has thousands of followers. It also says: "To find out how exercise and a balanced diet can help a healthy lifestyle" That is a fairly standard website run by United Biscuits, which owns McVitie's and is in turn owned by Yildiz Holding, a Turkish food conglomerate. It dishes out uncontroversial advice to eat a balanced diet and get some exercise.
Starch industry
When it comes to ingredients, McVitie's sets the tone and lists more than 30. It's hard to give an exact number and some are mentioned as "and/or". So they may or may not be there. The first ingredient on the list is glucose-fructose syrup and it makes up at least 19 per cent of the ingredients, though probably much more. In the European Union, the fructose content of glucose-fructose syrup is usually about 20 to 30 per cent and it is made from wheat or maize,according to the Starch Europe, a trade association that represents the interests of the starch industry. In the United States, it is often known as high-fructose corn syrup as it is predominately made from corn, and can be up to 50 per cent fructose. So it is similar, though not the same, as the type of sugar used in fizzy drinks in the US. Manufacturers love it because it can provide texture, volume, taste, glossiness, improved stability and a longer shelf life.