Bloomsbury Publishing 
Titles and Forms of Address [PDF ebook] 
A Guide to Correct Use

A
guide to correct forms of address in speech and correspondence. It
covers both formal and social occasions, and includes the forms of
address for bishops, peers, privy counsellors, ambassadors, JPs and
mayors. Where honours, decorations and degrees appear after the name as
letters, an explanation and the correct sequence is given. This edition
is revised and updated to cover changing conventions.

Now in its 22nd edition, this book has been in constant demand for over 85 years.