I picked up a copy of this book through Inter Library Loan. Seems like good fun reading! I wanted to try and ID the year my PW was made, but I haven't had much luck. I think it must be between 1910 and 1930, but its hard to get any closer then that. There are a few differences on the marks on my anvil then the ones outlined in the book. My "Solid Wrought" marking actually has circular lines around it, and my weight markings don't have the central number in the Solid Wrought circle.... Postman doesn't mention either of those types of markings.....
Anyway, cool book, I recommend it. I might have to purchase a copy now.