There is debate about whether hundreds and thousands (tiny round balls) or sprinkles are better.
No there isn't. Round sprinkles are the only option for fairy bread. Anyone who thinks otherwise is wrongity-wrong.
Pour on as many hundreds and thousands as you can get to stick. I do this in a baking tray to catch all the ones that fall off. Hundreads and thousands are the multi-coloured ball shaped sprinkles. These are the only permittable sprinkles to be used 
I find it neater to fill a plate with sprinkles and press the buttered bread into them. Saves them flying everywhere.
Sorry, dissenting voice from the Aussie Bush, here.
Hundreds and thousands may well be traditional for fairy bread, but they "crack" against one's teeth. Rainbow sprinkles are much better, because they "smoosh".
Seriously - I won't eat fairy bread if it's not sprinkles!
UNAUSTRALIAN! The crunch is what makes it awesome.
I'd never heard of fairy bread. Before finishing the thread, I was assuming it was something fancy and complicated too.
Question: You don't toast the bread so the margarine is melty? I can't wrap my head around the cold margarine... Can you at least warm the margarine?
No. Toast would steal the crunchy from sprinkles, and be less pliable to eat. Melted butter wouldn't stick the sprinkles to the bread and the colours would run.
Room temperature is fine - it doesn't need to be 'cold'. Just solidish.
when I first heard about fairy bread here - I thought it'd be something fancy/homemade. Then, when I googled it & saw the recipes were simplistic .... I thought I hadn't found the "real thing" so I asked here.
If DS were still young I'd make it, guess I'll have to wait until I'm a grandma.
Piffle. You don't have to make up a whol loaf. Just make a slice to taste.
If it was fancied up, it wouldn't be as good.