Here you can find information about all sorts of sussex poultry:

http://www.justsussex.com/

Characteristics
The Sussex chicken is an alert, docile breed that can adapt to any surrounding, they are comfortable in both free range or confined spaces. The breed sometimes (but not very often) goes broody, the speckled version is most likely to do so. They are good foragers.

http://www.enotes.com/topic/Sussex_(chicken)