Welcome to the HUG. I understand you perfectly. Good questions, thanks for the opportunity to do some research for you and to reply.
Yes, I think that there is a common origin for the Harbeth and Chartwell brand. There is also a connection with the Rogers brand. They are all intellectually rooted in the BBC 'school' of monitor speaker design. Harbeth was formed in 1977 and I believe that the Chartwell company was already in existance by then. I looked-up in my archive 'HiFi Choice, Loudspeakers' No.26/1881 and I see that by 1981, the Chartwell speakers were listed as Chartwell/Rogers and the factory address was that of the Rogers factory, Swisstone Electronics Ltd.. So I guess that by then, Chartwell had been absorbed into Rogers. I will see if I can find more information later.
Anyway, your question was about mounting the driver on or behind the baffle. First. let's show some pictures of this so we can be clear about the concept of flush or rear mounting.
TO BE CONTINUED;
Alan A. Shaw
Harbeth Audio UK