Taylor-Hobson and Cooke ser. VIIb puzzle

What is the difference, date of manufacture or other, of lenses engraved Taylor-Hobson Wide Angle Anastigmat Series VIIB and Cooke Wide Angle Anastigmat Series VIIB respectively ? I have a 6 1/4" and a 4 1/4 both in shutters so there is no serial number visible. I also have a 5 1/4 "Cooke" in barrel curiously engraved f/6,3 manufactured in the 50-ies if I remember Barbara's helpful answer to my query. By the way are there any rumors regarding the Series VIIC as yet, I have not had access to a computer for a period ?

Cheers, Richard

Can't help you directly, but View Camera Magazine had an article on Cooke lenses in, I think, 2002 that might be helpful. Both companies are still in existence, so their web sites might be of some utility.

http://www.cookeoptics.com/cooke.nsf/product/1890

http://www.taylor-hobson.com/thethstorybegin.htm