For the meringue, preheat the oven to 150C/300F/Gas1.
Whisk the egg whites in a bowl until soft peaks are formed when the whisk is removed.
Gradually add the sugar and continue to whisk until soft peaks are formed again. Spoon into a piping bag fitted with a small plain nozzle.
To make a template, draw four 20cm/8in diameter circles onto baking parchment and place on a baking sheet.
Starting in the centre of each circle, pipe the meringue in a spiral to fill the circle, keeping the meringue height as low as possible.
Cook in the oven for 20 minutes.
Turn the oven off but leave the meringues in there for at least two hours. When crisp, remove from the oven and leave to cool.
For the lemon curd, place the lemon zest, juice, butter and sugar into a bowl set over a pan of simmering water. (Don’t let the bowl touch the water).
Whisk occasionally until the sugar is completely dissolved then beat in the eggs and whisk until thickened and cooked through.
Remove from the heat and allow to cool completely.
Whisk the double cream in a large bowl until soft peaks form when the whisk is removed, then fold in the lemon curd and mix gently.
Spoon into a piping bag and snip the end off, giving a width of about 1.5cm/½in.
To assemble the cake, place a meringue disc onto a serving plate.
Pipe the lemon curd cream in a spiral onto the meringue to cover totally.
Place another meringue disc on top and repeat with the cream.
Repeat with the remaining meringue and cream, finishing with meringue on top.
Decorate with the fruit and serve in wedges.