Heat the milk in a pan with the butter then remove from the heat and leave to cool until it reaches hand temperature. Put the flour, bread improver if using, salt, sugar, yeast, spices and citrus zest into a bowl. Make a well in the centre. Pour in the warm milk and butter mixture, then add the egg. Using a wooden spoon to mix well, then bring everything together with your hands until you have a sticky dough (You can alternatively use a food processor or electric mixer)Tip on to a lightly floured surface and knead for 5 minutes until smooth and elastic. Put the dough in a lightly oiled bowl. Cover with oiled cling film and leave to rise in a warm place for 45minutes or until doubled in size. Meanwhile make the sugar syrup by placing all the ingredients into a small saucepan and boil together for a few minutes until the sugar dissolves and you have a thick glossy syrup. When ready, remove the dough from the bowl and knead in the tip the mixed fruit and mixed peel making sure everything is well distributed. Leave to rise for 1 hr more, or until doubled in size. Divide the dough into 15 even pieces. Roll each piece into a smooth ball on a lightly floured work surface. Arrange the buns on one or two baking trays lined with parchment, leaving enough space for the dough to expand. Cover (but don’t wrap) with more oiled cling film, or a clean tea towel, then set aside to prove for another 45 minutes. To make the cross on top, mix the flour and oil together with a little water to make the paste. Spoon into a piping bag with a small nozzle. Pipe a line along each row of buns, then repeat in the other direction to create crosses. Bake in the oven at 200`c for 20-25 minutes the middle shelf of the oven, until golden brown. When ready, remove the buns from the oven and immediately glaze with the prepared syrup. Leave to cool down slightly before serving.