If someone's drafting me and I have to pull out around something they may not have seen, I'll do the behind the back point after shoulder-checking.
If there's a pothole, glass etc just ahead, I'll point to let them know. Just seems like a courteous thing to do. Knowing that roads in London may have potholes is no substitute for someone pointing to one you'll be imminently encountering.
If someone's drafting me and I have to pull out around something they may not have seen, I'll do the behind the back point after shoulder-checking.
If there's a pothole, glass etc just ahead, I'll point to let them know. Just seems like a courteous thing to do. Knowing that roads in London may have potholes is no substitute for someone pointing to one you'll be imminently encountering.
I would draw the line at shouting things though.