Preheat the oven to 160°C, fan 140°C, gas 3. Grease a 20cm round deep cake tin and line the base and sides with a double layer of baking paper. Quarter the apricots, halve the cherries and chop the walnuts, then set them aside. Roll the marzipan into marble-sized balls, then set aside. Grate the zest from the oranges and squeeze about 150ml of the juice and set aside.
Put the butter and sugar into a large bowl and cream together until light and fluffy using an electric mixer. Gradually beat in the eggs, adding a little of the flour if the mixture begins to curdle.
Add the marzipan balls, the apricots, cherries, walnuts, orange zest and juice and sultanas. Sift the flour, baking powder and cinnamon into the bowl, adding any bran remaining in the sieve. Stir together until everything is well blended.
Spread the mixture in the prepared tin and level the top. Place the tin on a baking sheet and bake in the centre of the oven for 1 hour. Reduce the heat to 150°C, fan 130°C, gas 2 and bake for a further 1-1.25 hours until firm to the touch, starting to shrink away from the sides of the tin and a skewer inserted into the centre comes out clean.
Allow the cake to cool for 10 minutes in the tin, then turn it out on to a wire rack, peel off the lining paper and leave to cool completely.
To decorate, roll out the marzipan thinly on a worktop lightly dusted with icing sugar. Using an 11cm x 5cm holly-shaped cutter or template, cut out 8 holly leaves. Score a vein pattern with the back of a knife, brush the underside with a little water to help them stick and place 4 on the cake with another 4 overlapping on top. Shape the leaves to make them curl if preferred. Using a clean artist’s paintbrush, lift a little of the edible gold leaf on to the marzipan leaves to decorate. Roll any trimmings of marzipan into 3 berries, roll in gold leaf and place in the centre.