Put the clementines in a pan with some cold water, bring to the boil and cook for 2 hours.
Drain and, when cool, cut each clementine in half and remove the pips. Put the clementines – skins, pith, fruit and all – and give a quick blitz in a food processor (or by hand, of course).
Preheat the oven to gas mark 5/190ºC/375ºF. Butter and line a 21cm / 8 inch Springform tin.
Add all the other ingredients to the food processor and mix then finally adding the pulped oranges.
Pour the cake mixture into the prepared tin and bake for an hour, when a skewer will come out clean; you’ll probably have to cover with foil or greaseproof after about 40 minutes to stop the top burning.
Remove from the oven and leave to cool, on a rack, but in the tin. When the cake’s cold, you can take it out of the tin.