Pre-heat your oven to 180°c (160°c for fan assisted oven, Gas Mark 4 or 350°F). Line a 2lb loaf tin with a loaf tin liner, or some greaseproof paper. Set aside. In a large bowl, cream together the margarine/butter and sugar, until it is light and fluffy.
Add the eggs one at time, ensuring each is mixed through before adding the next. Add the orange zest, vanilla, marmalade & milk, mixing to combine.
Sift in the flour, before gently folding to create a batter.
Transfer the batter to your pre-lined loaf tin and bake in your pre-heated oven for 45-55 minutes until risen, golden and a skewer inserted comes out clean.
Whilst since warm, spoon a little excess marmalade on top and spread over with a spoon to create a lightly glazed top. Allow to cool completely in the tin, before removing and serving in slices.