That's a pretty impressive portfolio of designs - https://en.wikipedia.org/wiki/Frank_Stephenson
On the Mini.. well, it a contentious one amongst car fans. Issigonis was trying to design something cheap, small on the outside and big on the inside all while using as much from the BMC parts pin as possible. The fact that it was cute to look at and fun to drive were rather pleasing secondary factors.
When *Rover* tried to redesign the Mini in the late 1990s, they came up with a number of things which were closer to the Issigonis idea of efficient packaging (some looked like the Daewoo Matiz), where BMW was more interested in the cuteness factor. In the end, BMW won and the Mini was a huge success.
There's an interesting and more detailed story about the development of the Mini and the prototypes that never made it here: http://www.aronline.co.uk/blogs/cars/mini-bmw/mini-2/the-cars-mini-development-history/