Add the pink food colouring to one of the bowls of cake batter and stir to mix through evenly
Spoon the pink batter into one of the prepared loaf tins and the remaining uncoloured batter into the other loaf tin
Smooth the surface of both cakes and place in the oven. Cook for 40 minutes or until a skewer inserted in the centre of the cakes, comes out clean.
Remove from the oven and leave to cool in the tins. Once completely cool, unmould the cakes and removed the baking parchment.
Trim off all the edges of the loaves, squareing off the edges.
Cut each loaf in half vertically along the length and in half again horizontally giving 4 long rectangular pieces of each cake.
Spread a thin layer of the damson jam on one long edge of a piece of lemon sponge cake and sandwich together with a piece of pink sponge. Repeat this process with another strip of lemon and pink sponge. Place 1 pair of jammed sponges on a board so they are flat. Spread a little more jam over the top, then place the other strip of jammed sponge on top so the sponge colours are alternated forming an oblong loaf. Repeat this process with the remaining sponge.
Cut the marzipan in half and roll out one piece, dusting with icing sugar as needed to prevent sticking. Roll the marzipan into a piece large enough to enclose the battenberg loaf.
Spread a little more jam over the surface of the marzipan. Place the prepared jammed sponge onto the marzipan then carefully roll up so the marzipan encloses the cake, with the joining seam on the bottom of the cake. Trim off any rough edges. Set aside.
Repeat this process with the remaining marzipan and jammed sponge.
For small Battenbergs, simply cut the sponges into smaller strips and use the same process to assemble. Slice to desired thickness and serve.