Put the rhubarb into a pan with 100g/4oz sugar and the honey and cook over a low heat for 15-20 minutes until completely softened. Taste and add more sugar if necessary. Spoon the rhubarb into a sieve set over a bowl. This will release some of the rhubarb juices, which will provide a syrup. Leave until cold.
Whip the double cream to soft peaks. If the rhubarb pulp is very pale, mix in a little grenadine to give it more of a pink tone. Now mix the coconut cream into the rhubarb
pulp, and add 100ml/3½fl oz of the rhubarb juices. Lightly fold in the cream, leaving the rhubarb with a rippled effect.
Divide the mousse between 6 glasses and firm them up in the fridge. This should take a couple of hours, but they will keep for up to 24 hours. When you’re ready to serve, top each mousse with a trickle of rhubarb syrup, a broken macaroon and a sprinkling of coconut.