Here's the official website for the proper use of Forms of Address It is written and maintained by a former government official, Robert Hickey, who conducts seminars for those who need to address important people properly.

On the subject of "President", he says that properly, only the sitting president should be called "President", same for any position held by only one person at a time, out of deference to the person who holds the office. For officials such as Senators, Judges, etc, of which there are many, it is ok to use the title after they've left office.

I find it odd that you think America is more deferential to titles that the UK. From our point of view, you have that whole peerage thing where people are given titles just for the sake of having titles;-)