The England on the tang came around 1891 IIRC due to trade or import reason. Country of Origin I believe. And as a guess these are from around 1840s to late 1890s. The FBO or for barbers only pre date the FBU. This is all of memory serves me correctly. Can't wait to see a pic and congrats on a fantastic score! And what a deal!
The only FBO I have seen have been on later models of WB razors. FBU goes way back, at least into the 1830s. The big-blade FBU have been on a number of distinctive blade styles.