Keep to the left – as the sign above says! I do find it amazing that so many folk do not ‘get’ this; we drive on the left, apart from the middle-lane hoggers on motorways, so we walk on the left.
In Fernie (Canada) the kids learn from their parents that they walk/ride on the right and as soon as they see you coming they all move to the right as a herd – there is no dithering or splitting to both sides or moving to one side and then changing their mind!
I always call out “is there room for a bike please?” and then wait for people to decide which side they would like to move to this time before passing.
Now, dog walkers calling out to their dogs to ‘move out of the way’ is another topic alltogether.