Thanks for the reply Hinso. The problem is that when I select a standard place (I usually get the drop down list by adding a space to the end of the place name, but removing the "m" from "United Kingdom" would do the same) and select one of them, it is not being flagged as being standardized after the dialog closes.
It didn't use to behave this way, Family Search are constantly tinkering with the user interface on their site, and generally the changes are big improvements. For example the way that merging people works now is much better than it used to be.