The Berkeley Differential

This section has more questions than answers. The Berkeley differential is an interesting design, but it wasn't unique. Roger Brundle from Australia recently pointed out that it is similar to the Austin 7's, and that modern Qaife torque biasing diff is a helical gear refinement of the 7's. Was this general design used in other cars? Was it a common pre-war design?

Notice the similarities between the Berkeley unit pictured above, and the Austin 7 diff shown at right.