Some feedback on your change:

1. I may be misunderstanding the direction tag so apologies if that is the case but I believe it is suppose to indicate the facing orientation of the feature. With traffic signs, they face against the direction of travel so if you encounter a traffic sign when traveling north then the sign is facing south. So the maxspeed sign added to Shetland Case, drivers encounter the sign as they travel northbound (confirmed via bing streetside imagery) so the orientation would be south but you have it tagged direction=N. 

2. It appears you may have duplicated traffic signs by creating standalone nodes for some stop signs that were already tagged via a node on the way. The intersection of Shetland and Pony Chase being an example. I believe this is considered undesirable per the one feature one osm element guideline.

3. I noticed that the maxspeed is not tagged on the ways themselves in some cases where you added maxspeed traffic sign. Most software that use osm data for routing or turn by turn navigation would likely not take into consideration the maxspeed information from the traffic sign when mapped as a single node like done here. For this reason, it is usually desired when mapping a speed limit sign to always add a maxspeed=* tag to the way / section of road applicable. 

4. I see in another edit you did tag maxspeed:forward on ways in this general area. However, a quick look through streetside imagery suggests that it should be just maxspeed as the speed limit affects both directions of travel on the road.

Hope you found this review helpful. If you have time, I'm looking for folks to review my changes. Let me know if you spot any potential issues in my changes or otherwise have any suggestions or tips.