Weka, L says your ingredients are right but adds:
No baking powder, just use equal
weights of cornflour and sugar with one egg to every 35 - 40g of sugar. So four eggs needs about 150g of sugar as well as 150g of cornflour. The eggs and vanilla are beaten on high till thick and creamy then the sugar is added in spoonfuls and each one beaten on medium till each batch of sugar is dissolved followed by a final blast on high. The cornflour then needs to be sieved and folded in very carefully with a non-metallic spatula.
Cooking is done in a fully preheated oven at 180ºC - middle tray.
Apparently another trick is to make a meringue with the egg whites, sugar and a pinch of salt before mixing in the yolks and then sieving in the cornflour with a pinch of baking powder. Also other flavours can be used such as almond essence, cherry, lemon, coffee etc.
She says they do rise but if making something like a Victoria sponge sandwich you will need two. Well buttered 20cm tins are about the right size.
I'll ask about tips on gluten free once Michael and Sophie move out to London, it is a bit stressful atm.
Kaz, I forgot about rice flour, it is used in lots of Chinese cooking, and they do love their cakes.