Bicycle symbols painted on the roads
I've cycled in London for six years and have seen more and more painted bicycle symbols on the roads recently.
These are not in designated cycle lanes, nor the larger ones you see in advanced stop lines. I've attached an image of the sort I mean -- on certain roads you see them every 100m or so, about 1/3 into the road from the pavement. Can anyone inform me, or point me to a resource, that explains the thinking behind this paint? I'd love to know if there's a policy.
To me, they're examples of a shoddy compromise on roads where it'd be too costly to implement "proper" cycle lanes, or some kind of attempt to raise motorists' awareness that they should expect bikes to share the road with them (why only those ones in particular?).
I apologise if this has been widely covered already. Searching the forum turned up nothing, and as you can see, it's my first post.
I'd also be interested to hear if anyone has different opinions about their efficacy. Thanks, Sam