British Intelligence objectives sub-committee book on German race cars of the 30s

http://forums.pelicanparts.com/9447323-post36077.html

Teams of experts were sent into Germany post WW2 by allies to pick brains of German tech staff.

Included in this was racing teams. Buried in that doc. Is description of downforce device engaged during cornering. Some years before Chaparral. Although it was relatively small, not a big wing on top.