That is almost the same as my recipe from GN. You need cream because there is no butter, so rubbing in not needed.
I use double Elmlea cream and the lemonade mustn't be diet. Mix lightly, cut and bake at 220C for 10-12 mins.
I sometimes add a little sugar to the mix, but if you are topping with plenty of jam there is no need.
If anyone is interested, I have adapted the recipe to make cheese scones, which are also very light:
14 oz SR flour
6oz double cream
6oz lemonade (not diet)
Grated cheese
pinch of salt
a slosh of oil (optional) for extra richness.
Mix lightly, shape and bake at 220C 10-12 mins.