Cake flour (低筋粉) is very soft and fine, and almost feels like silk,
has a lower protein content 6-8%, plain flour has 8% to 11% protein (gluten).
it is possible to reduce the protein content with cornflour.
Tesco Plain Flour
Tesco Medium Food
& Freezer Bags Zip Slide
Add 1 cup plain flour into a zip-top plastic freezer bag.
remove 2 tbsp plain flour and add 2 tbsp cornflour instead.
So, if your recipe calls for 2 cups of cake flour,
measure out 2 cups of plain flour, remove 4 tablespoons,
and add 4 tablespoons of cornflour.
Mix together your plain flour and cornflour ,
about six to eight times.
Now, You're Done!
In fact, I've never seen cake flour in the UK, it doesn't seem that readily available,
anyway, you can purchase cake flour online at Amazon or Ebay.co.uk
but it was much more expensive than plain flour sold in the store.