Combine the water, cornflour and cherry liqueur in a medium-sized saucepan and place over low heat. Stir until the cornflour dissolves and no lumps remain.
Stir in the cherries and Whittard Sour Cherry Tea (or granulated sugar).
Turn the heat up to medium and bring the mixture to a simmer while stirring frequently.
Once the compote is thick and bubbling, remove from the heat and pour into a bowl. Place in the fridge to cool completely.