Add all ingredients, other than garnishes, to a large pan and stir to combine.
Cook on the hob over low heat and slowly bring to a very slight simmer, trying to avoid allowing the mulled wine to bubble too much. As soon as it comes to a low boil, decrease the heat to its lowest possible and simmer gently for at least 30 minutes.
Taste the mulled wine and add more honey if need be, then strain into a clean pan or jug for serving.
Serve warm in heatproof glasses or mugs, then garnish with orange slices cut into half-moon slices.