place the ground almonds, caster sugar and icing sugar in a bowl and mix together
in another bowl whisk the egg whites with the lemon juice, sherry and vanilla essence, then add to the dry mixture
stir well to mix and knead with your hands until smooth
this will make 900g of marzipan
first double line a 23cm round, loose based cake tin with greaseproof paper
put all the fruit except the cherries in a saucepan with the lemon rind, juice and port
bring to the boil, stirring all the time; remove from the heat and stand the saucepan in a bowl of cold water to cool the fruit quickly
place the butter, flour, eggs, treacle and spices in a large bowl and beat together well
fold in all the soaked fruits and the nuts until well combined
finally stir in the cherries, being careful not to break them
turn into the lined tin and flatten the top
bake at 150C/Gas2 for 3 hours or until a skewer inserted into the centre of the cake comes out clean
cool overnight in the tin then turn out and remove the lining paper
decorate to your taste