Cut the watermelon into neat bite-sized cubes. I found that the easiest way to do this was to cut the melon into thick rounds, then cut each round slice up in a grid pattern.

My boys enjoyed eating all the odds and ends as we went along, but you could also pop any trimmings into a bag (minus the outer skin!) and freeze for use in smoothies at a later date.

Line a baking tray with grease-proof or baking paper (check that the tray fits into your freezer first!) then lay out the watermelon cubes, taking care to ensure that they aren't touching each other.

Freeze for a couple of hours or overnight.

Once frozen, peel the paper away and pop the frozen melon cubes in a freezer bag to store in the freezer until ready to use.

When ready to serve, fill a glass with melon ice cubes and pour over sugar free lemonade to serve.