Information and discussion on all aspects of British photographic history
Hi Richard, Yes, Bradford would be a good bet, but also look into the Kodak archives recently donated to DMU as mentioned by the blog creator here. There appears to be quite a lot of information that may be useful to your research. Also, no expert here - but there is a book that focuses on Eastman's brilliant marketing of Kodak cameras from the first Kodak camera in 1888 through the 1930s. It's written by a Nancy Martha West and entitled 'Kodak and the Lens of Nostalgia"
Lastly, a really beautiful collection of old vintage camera ads, including Brownies, can be found here.
Looking forward to another BPH blogger (Belinda May)'s site - Poster Collection at PARC - to be equally as impressive in the near future.
Hope info is of use, for what it's worth. Good luck with your research !