If a car on the opposite side of the road overtakes a cyclist too closely (due to the oncoming traffic) my instinct is to move left and give them a bit more room - for the cyclist's benefit, really
I'm wondering if facilitating an illegal/dangerous manoeuvre is appreciated though; perhaps it's wiser to stay on course to discourage the overtake entirely... which obviously comes with the risk of them just overtaking the cyclist even more closely
I think the old "it's not your job to police the roads" comes into it here as well
Is there a consensus?
I would not class moving over as policing the road, OK you moved over because someone was being stupid and deserved to be booked for careless or inconsiderate driving.
How would you have felt if the cyclist had fallen off, and you had not tried to make room?
You could dismiss it as nothing to do with me but at the back of your mind I am sure you would be thinking, what would have happened if I had made more room?
No, I would define policing, as chasing after the offender, and attempting to point out the error of their actions, definitely asking for trouble.
There are situations where I feel some 'interference' is justified, say driving along a country road and a car catches up, and they usually get too close behind, so I then change to long braking approaching corners, occupying more road when it is not safe to overtake, and making lots of space when it is safe to overtake. Should the follower insist on overtaking when it is unsafe all I can do is assist as much as is possible.