To clean the drain, tip the baking soda down the drain as best you can then pour over the white vinegar.

The chemical action will lift anything that's lurking in the drain that will usually be dirt, grease and grime.

Once it has completely stopped bubbling, pour down the complete kettle of freshly-boiled water.

The hot water will dissolve and wash away the grease leaving you with a nice clean-smelling sink.

If it's still a little smelly after the first go then you can repeat the process but I haven't needed to before.