Preheat the oven to 180 ºC (350 ºF).
Butter two round cake tins, one 26 cm and the other 20 cm in diameter, and a 20 cm square cake tin or spray with non-stick spray.
Sift together the dry ingredients. Mix the remaining cake ingredients and add to the dry ingredients. Mix well and turn some of the batter into the two round tins.
Turn the remaining batter into the square cake tin. Bake for about 15 to 20 minutes (for the square tin) and 40 to 45 minutes for the round cake tins or until a testing skewer comes out clean when inserted into the centre of the cakes.
Leave to cool in the tins before turning out to cool completely.
Cream the butter, sifting in small quantities of the icing sugar while beating continuously.
Add the egg and beat until creamy.
TO DECORATE THE CAKE:
Enlarge the clown face and hat and glue to sturdy cardboard if desired.
Trace the eyes and mouth on another sheet of paper and cut out.
Place the clown face on top of the large cake and cut out carefully along the outline.
Cut out the hat from the smaller cake.
Place the two cake layers against one another at the top end of a large tray or chopping board, leaving enough space for the hat's tassle.
Cover the face and sides with icing, spreading it evenly with a spatula dipped in boiling water.
Add a little green colouring to some icing and spread evenly over the hat section.
Add a little yellow colouring to a little icing to obtain a pale yellow colour and decorate the rim of the hat.
Place the paper cut-out on the face again and mark the important paints such as the mouth and eyes with cocktail sticks. Remove the paper cut-out. Position the paper mouth on the decorated face.
Trace lightly with a cocktail stick all around the outline and remove the paper. Repeat for the eyes.
Mix a large quantity of icing sugar with water to form a thick paste that spreads easily and spread between the outline of the mouth. Repeat for the eyes. Leave to dry.
Spread a little of the icing sugar paste on the top of the hat on the tray and arrange the wafer biscuits on their sides in a circle to form a tassle. Spread paste on the sides of the head and arrange Niknaks on the paste for the hair.
Colour the remaining icing sugar paste deep red and spoon into a piping bag with a thin nozzle. Pipe the outline for the mouth and eyes, colouring in where necessary. Pipe along the outline of the face and hat.
Position the apricot sweet where the nose should be and use the liquorice sweets for pupils. Decorate the hat with Astros and place a red Astro in each corner of the mouth.
Cut the square cake into small squares and decorate these and the leftover pieces of cake with the remaining icing sugar. Place the pieces of cake in the surprise packets. If desired, make a clown suit with fabric and stuff with newspaper.
Use the printed kids' hands as hands. Make a collar out of a strip of white fabric, gather with string or elastic and tie around the top of the clown body. Place below the clown face.