Written by Alexander Frater, an Australian, who had a 'thing' for flying boats and in the '70s or 80's repeated the journey from London to Sydney, going via as many of the old flying boat stations as possible and describing how life would have been during the flying boat era. I found it fascinating and hard to put down.
Out of print now but you should be able to get a copy here:
http://www.abebooks.com/