Watermelon Ice Lollies

For the UK, summer is almost here, and the bottom draw of my family's freezer is full of lemonade and orange ice lollies which I eat on most days.  Years ago, we had some ice lolly moulds and I think it would be a good idea to use them to make some delicious fruit lollies.  I found the following recipe for watermelon ice lollies in The Icecreamists by Matt O'Connor.  Due to the possible use of bone char in the process of making the caster sugar in the recipe, I'm not sure how suitable it would be for vegans.  Have a great week!

Ingredients (to make 6-8 ice lollies)
100ml (3 1/2 fl oz) water
100g (3 1/2 oz) caster sugar
flesh from 1 watermelon, seeds discarded
juice of 1 lime

Method
1. Pour the water into a pan and add the sugar.  Place over a low heat and bring to the boil, whisking constantly, until the sugar dissolves.  Reduce the heat and allow to simmer for 5 minutes, continuing to whisk until the liquid turns has the consistency of a syrup.  Set aside and allow to cool for 10 minutes.
2. Put the watermelon flesh in a blender, pulse until crushed, then sieve into a measuring jug.  You should have around 500ml (17fl oz) of juice.
3. Add the watermelon juice and lime juice to the syrup and whisk together.  Pour into lolly moulds, filling them about two-thirds full so that the mixture is able to expand as it freezes.  Place in the freezer for about 30 minutes, until almost solid, then insert a stick in each one.  Freeze for another 30 minutes.