Pre-heat the oven to 200°C / 180°C (fan) / gas mark 4.
Grease and line the baking tin.
Sift the flour and xanthan gum into a bowl.
Rub in the margarine / butter.
Add the sugar, cinnamon and ginger.
Add the egg, sultanas and grated carrot and mix.
Add the milk - you want quite a wet mix as the gluten-free flour absorbs more liquid.
Add to the cake tin, level it off and place in the oven.
Cook for around 40 minutes - until golden and a skewer comes out clean.
Leave to cool in the tin before serving (ideally with a cup of tea!)