Sift together the flour, baking powder, baking soda and salt. Cream sugar and butter until smooth.
Beat the eggs. Add one at a time. Mix the lemon juice and milk. Fold in a ⅓ flour and a ⅓ lemon juice and milk liquid, repeat. Beat in the vanilla essence.
Pour into greased pan and bake in a 350 degrees Fahrenheit oven until it leaves the sides of the pan.
Alternatively, test with a thin knife; insert in the centre of the cake, if it comes out clean the cake is done.