Talk to cyclist about Vehicle Cycling and ‘Primary Position’ will get mentioned. It is a way to control the traffic behind you and force it to change lanes to pass you safely, adopted in situations when there is not enough space to overtake safely. It can be used on multilane roads to force road users behind you to change lanes and used on single track roads to prevent other people from passing you unsafely.
There are certain situations where you can get away with not taking primary position, such as with a traffic island. A gesture that you are indicating right will force road users behind you to halt their actions and prevent them from overtaking.