Preheat the oven to 170°C/325℉ gas mark 3, slipping in a baking sheet at the same time.

Spray the inside of your bundt tin with non-stick cooking spray, or brush on a paste made of 2 teaspoons of plain flour mixed with 2 teaspoons of oil.

Combine the flour, baking powder and bicarb in a bowl, and fork to mix.

Put the butter in the bowl of a freestanding mixer or a regular mixing bowl, grate in the zest of both lemons and beat until creamy.

Strip 4 tablespoons/¼ cup of thyme leaves from the sprigs, and add along with the caster sugar, and beat again until you have a light fluffy mixture.

Now, one by one, beat in the eggs and, after the last one, slow down your mixing and add a third of the flour mixture, followed by a third of the buttermilk, and so on until both the flour mixture and buttermilk are used up.

Finally, beat in the juice of 1 of the lemons and transfer this mixture to the prepared bundt tin.

Place on the baking sheet in the oven and bake for 1¼ hours, though start checking after 1 hour.

When a cake tester comes out clean, remove the cake to a wire rack and leave in its tin for 15 minutes before carefully unmoulding.

When the cake is cool, slip the piece of newspaper or baking parchment under the wire rack, then sieve the icing sugar into a bowl and beat in the juice of the remaining lemon until you have a glaze that is thin enough to run down the cake.

Duly pour the sherbetty glaze over the cake, and immediately scatter with thyme leaves.