Since you responded to my post about the time-period of your Georgia State Seal button's backmark by posting a photo of the backs of the Old-English ("Script") I button and South Carolina State Seal button, I assume you want time-period info for those two backmarks. Both of them were manufactured in England for sale to the Confederacy, and shipped over here through the yankee naval blockade on a Blockade-Runner.
"HT&B Manchester" is the firm of Hammond, Turner, & Bates -- a button-manufacturing company whose office was in Manchester and factory was located in Birmingham England.
"S. Isaacs Campbell & Co / 71 Jermyn St. London" was a major supplier of military equipment to the Confederacy.
The above information is from the book "American Military Button Makers And Dealers; Their Backmarks & Dates" by William F. McGuinn & Bruce Bazelon. It is the absolute best book for time-dating the buttons we dig by the backmark. It covers backmarks from late-1700s through the modern era. Cost is about $25 to $29, and well worth the money.