Put the sultanas and currants in a heatproof bowl then pour over enough hot black tea (or flavoured tea or hot water) to more than cover. Set aside until cold then drain and place on kitchen paper to dry.

Preheat the oven to 180°C /160°C Fan /Gas 4 /350°F with a shelf in the middle.

Butter and/or line a non-stick rectangular baking tin approximately 26 x 16 x 4 cm or one with a similar capacity.

Sift together the flour, baking powder, ground mixed spice and salt then set aside.

Put the soaked and drained dried fruit on a plate or shallow bowl and toss with a little of the spiced flour.

In a large bowl and preferably using electric beaters, beat together the butter and sugar until soft and light. Scrape down the sides of the bowl as necessary during this and subsequent steps.

Beat in the eggs one at a time along with approximately 1 tbsp of the spiced flour mixture each time.

Beat in the milk a tablespoon at a time with another tablespoon of the spiced flour each time.

Fold in the remaining spiced flour plus the dried fruit.

Transfer the mixture to the prepared tin, spreading out evenly and smoothing down the top.

Sprinkle over the sugar nibs or Demerara sugar.

Put in the oven and bake until risen and golden brown: when done the edges should be pulling away from the sides of the tin, the top springy when lightly pressed, and a skewer or cocktail stick should come out clean (approximately 25 min).

Tip: check after 18 minutes and if the bake is browning too quickly before it's set, turn the temperature down a little.

When done, transfer the baking tin to a wire rack and leave to cool for 5-10 minutes.

Carefully remove the cake from its tin and put directly on the wire rack. Leave until completely cold before slicing into 12 oblong pieces.

Store in an airtight container. Best eaten within 3 - 4 days.