Could you please tell me if it is possible to use strong bread making flour when baking a cake when the recipe calls for plain flour.
Flours are different in their protein content. More protein means more gluten means more structure. Strong bread flour has a lot of protein, cake flour has very little, so a cake made with strong bread flour will not be as light and fluffy as with all purpose (medium protein) or cake flour. If all you have is the bread flour and you want to bake a cake, you can cut it with corn starch (see link below).