In a large bowl, beat together the margarine, milk, eggs and sugar. Stir in the flour, baking powder, bicarbonate of soda and salt. Carefully fold in the blueberries and walnuts. Fold in lemon zest.
Spray bread machine pan with cooking spray. Pour mixture into bread machine pan and put pan into bread machine. Select Quick Bread/Cake cycle, and press Start. Check in 1 minute to see if mixture is well blended. Cook until cake cycle stops. Cool completely in bread machine pan before removing.