Start by making the cake. Heat oven to 180C/160C fan/gas 4 and lightly grease a 23cm deep round cake pan, lining the base with parchment paper.
Cream the butter and sugar together in a large bowl using an electric hand whisk until light and fluffy – this should take about 10 mins. Add the vanilla and whisk again to combine. Beat the eggs a little with a fork, and with the beaters still running, add the eggs a little bit at a time. Wait until each addition has been fully combined before adding more.
Once all of the eggs have been added, fold in the flour with a spatula in three additions, alternating with the yogurt. If the finished batter feels a little stiff, mix in a couple tbsp of milk to loosen it. Transfer the batter into the prepared cake pan and level out with a spatula.
Bake in the preheated oven for about 1 hr 30 – 1 hr 40 mins or until a skewer inserted into the middle of the cake comes out clean. If the cake is browning too quickly, cover loosely with baking parchment for the last 15 mins of cooking. Allow the cake to cool in the tin for 20 mins.
While the cake is cooling in the tin make the syrup. Place the sugar, 50ml water and vanilla extract into a small saucepan over a medium heat and bring to a simmer, cooking for a few mins until the sugar has dissolved. Transfer the cake onto a wire rack to cool completely then use a skewer to poke holes all over the top of the cake. Use a pastry brush to spread the syrup over the top of the cake, allowing it to soak into the sponge before adding more.
To make the buttercream, beat the butter and icing sugar together with an electric hand whisk until light and fluffy, then add the orange curd and whisk again to combine. If the cake is domed on the top, use a large serrated knife to level it off then cut the cake through the middle, into two layers. Place the bottom layer of cake onto a 23cm round cake board and spread a thin layer of buttercream on the cake and top with the raspberry jam. Place the second layer of cake on top and spread the remaining buttercream over the top and sides of the cake.
On a work surface lightly dusted with icing sugar, knead the red sugarpaste until soft and pliable. Roll it out until about 3-4mm thick and wide enough to cover the cake. Roll the sugarpaste onto the rolling pin and carefully drape over the cake. Gently smooth the sugarpaste down the sides of the cake and trim off the excess with a small sharp knife. Reserve the trimmings for the details later on.
Repeat the rolling process with the yellow sugarpaste but this time cutting into thin strips. Cut 30 strips approx 1.5cm x 10cm and stick to the sides of the cake all the way around, dipping your finger in water to brush onto the back of each one, which will act as glue (the strips should cover the entire height of the cake but only reach a couple of centimetres over the top of cake).
Next roll out the blue sugarpaste to the same thickness as the red and yellow but this time cut out a 20cm circle and stick it in place in the middle of the cake using a little water. Roll out the brown sugarpaste as well and use a thin sharp knife to cut out Duggee’s face and attach to the blue circle.
For Duggee’s clothes knead a little yellow into the remaining brown sugarpaste until it is a light brown colour and use this to cut out his shirt and lip area, sticking with a little water as before. Use the black sugarpaste to roll his eyes and nose, using your hands rather than rolling on the work surface. Use the remaining sugarpaste to shape the decorations for his outfit and mouth and stick as before with a little water. Wrap the ribbon around the bottom edge of the cake and secure with tape or a pin but remember to remove before serving. This cake will keep in a sealed container for up to 4 days.