There is quite a lot of information on the Internet relating to the Staffordshire Potteries, and most of them also made these little china flowers brooches, but I just thought I'd give you a quick insight into the history.  
The bone china flowers had been made to decorate pottery since the middle of the 18th century.  During Victorian times these bone china flowers were also becoming popular as jewellery in particular as keepsake brooch and other items of jewellery decorated with a variety of tiny handmade flowers.
The bone china flowers were made by hand and it was very delicate work done by the female workers who worked at the pottery factories as assistants to the men.  
You can find an interesting article by Vivien Young about women who worked in the potteries here: Women in the Potteries: The Bone China Flower Makers by Vivien Young
Here is a short list of some of the makers of china brooches that I've come across (for a more complete list of the pottery makers of Staffordshire, you can find this here: A-Z of Stoke-On-Trent Potters 
Adderley Floral China - from 1936 to 1988.
Aynsley - from 1945 to 1968.  In 1969 Aynsley acquired Denton China.  In 1971 it was renamed Aynsley China.  From 1989it has been retailing as Hammersley China Ltd.
Coalbrook - traded in 1954 (see also Coalport China).
Coalport - from 1951 as Coalport China Ltd.  From 1963 as Coalport.  Now part of the Wedgwood Group.
Crown - 1946 it was Crown China Crafts.  From 1948 to 1985 is was Crown Staffordshire China Co Ltd.  In 1973 it became part of the Wedgwood Group.  From 1985 the title Coalport Ltd started to be used instead of Crown Staffordshire.
Denton China (Longton) Ltd - traded in 1954.
Dresden Floral China - traded in 1945.
Royal Albert - joined the Royal Doulton Group in 1971.
Royal Doulton - from 1882 to 2005 traded as Doulton & Co Ltd.  Joined the Wedgwood Group in 2005.
Thorley China Ltd - traded in 1940.