Grease and line a 9" springform tin. Preheat oven to 140C/120C fan/gas 4.
Beat the margarine until soft using an electric mixer. Add the sugar and cream the two together until pale and fluffy.
Add the eggs bit by bit, whisking and adding a little flour as you go to hold the mixture together. Do not overbeat whilst adding the eggs – you just want to combine the ingredients.
Once all the egg has been added, add the rest of the flour and give the batter a good beating in your mixer.
Sprinkle the spices, ground almonds, lemon juice, and lemon and orange rind on top of the mixture and fold in until evenly distributed. Add a pinch of salt for luck.
You can toss all the dried fruit in a handful of flour before adding it to the mixture, as that helps prevent the fruit sinking. Fold the dried fruit into the mixture and then pour the mix into the lined tin.
Place on the middle shelf of the oven and cook for 2 hours. Depending on your oven, the fruit cake may take a little more or less time. Test the cake after 1.5 hours by inserting a skewer or sharp knife into the centre of the cake - if it comes out clean, it's ready. Leave to cool in the tin.
To decorate: Knead the marzipan to soften and mould it into a square block. Using a rolling pin, press firmly down to flatten out the marzipan, keeping the pressure even. Turn the block 90 degrees and repeat.
Continue this process four or five times, then roll the marzipan out into a circle big enough to cover the entire cake. The marzipan should be the thickness of a pound coin.
. Warm 3tbsp apricot jam in a microwave or saucepan. Do not bring to the boil. Pass warm jam through a sieve to remove clumps of fruit.
. Brush the top and sides of your cake with jam. This will allow the marzipan to stick to it properly.
. Dust your rolling pin with icing sugar and place it at the top end of the rolled-out marzipan. Gently roll it towards you, folding the marzipan over the rolling pin as you go.
. Flop the marzipan over the cake, making sure it completely covers the sides. Using a very sharp knife, carefully cut around the cake, leaving the leftover marzipan behind.
. For the royal icing: Place the egg whites in a bowl then stir in the icing sugar a spoonful at a time. It should fall thickly from the spoon. Whisk for 10 minutes with an electric mixer until the icing stands up in stiff peaks, then stir in the glycerine.
. Spread the icing all over the top and sides of the using a palette knife, listing it up at intervals to create a peaky effect.
. Refigerate cake for at least 30 minutes (no longer than an hour) before decorating with an array of Christmas tree decorations.