Hello Chris,
I am also descended from Mercy Noakes through to Charles Hermann, who was my ggrandfather. Charles' son Ernest Victor Hermann was mt grandfather.
I have a bit of information on the Hermann's and some detail on the Noakes line as well.
You may want to have a look at
http://sarahcullen.net/ where you will find a lot of Hermann family tree info, photos and documents.
Regards
Paul Hermann