Preheat the oven to 200C/400F/Gas 6.
Place the dates, bicarbonate of soda and enough water to cover the dates into a saucepan over a low heat and cook very slowly, stirring occasionally, until the dates break down and form a sticky sauce.
Sift the flour and baking powder into a bowl and add the sugar.
Rub the butter into the flour mixture and then add the egg and mix together.
Gradually add the milk, stirring constantly, until a smooth dough forms.
Add the date mixture to the dough and mix together well.
On a clean, flat, floured surface, roll out the dough to 2.5cm/1in thick, then, using a pastry cutter, cut into 7.5cm/3in rounds.
Place the rounds of dough onto a greased baking tray and transfer to the oven to bake for 8-10 minutes, or until risen and golden. Remove from the oven and cool on a wire rack.
To serve, cut the scones in half. Mix the lemon curd and banana together in a clean bowl, then spread generously onto one half of each the scones. Top with clotted cream, place the scone tops on top and arrange on a large serving plate.