Line a cupcake tin with 12 large cases.
Heat the oven to 180°C, 160°C fan, gas 4.
Put the butter and sugar in a bowl and beat with an electric whisk until light and fluffy. Gradually beat in the egg, buttermilk, oil and vinegar.
Add the flour, bicarb and cocoa with a large pinch of salt and beat everything together until smooth. Lastly beat in the red food colouring, adding extra if needed to produce a deep red mixture.
Spoon the mixture into the cupcake cases and bake for 15-20 minutes, or until a skewer inserted into the centre comes out clean.
Meanwhile make the frosting. With the electric whisk, gradually beat the icing sugar into the butter. Add all the soft cheese and beat together for a good 5 minutes until light and fluffy.
Pipe or spread the cold cupcakes with a ring of the frosting. Spoon the conserve into the centre and decorate with sugar crowns.
Union Jack cupcake cases are available online. Food colouring gels are available in supermarkets, the paste from specialist cake shops.
To make the crowns, thinly roll out flower paste (available is major supermarkets) and cut out strips approx., 7.5cm x 5cm. Cut a zig zag pattern across one length. Roll the strip into a crown shape and seal the edge with a little water. Leave to dry and harden. Glue edible silver balls to the peaks with edible glue.
