I'm rather suspicious of how well the cabin has held up considering the damage to the front end! I would have expected the roof and A-pillar to have buckled up, as seen in many photos of pranged minis 
The thing is that hiting something solid square on will leave the car fairly intact as it spreads the load across the whole car, what is more realistic is hitting the car on one corner and sadly this causes a lot more damage.
I gotta say, that's an aspect of these staged tests that I think de-validates them, that they are staged tests and often not close to the real world. I was only yesterday reading up on one type of side impact test that appears unique to Australia. The Test I feel is way removed from reality and it has actually been the cause of some makers pulling models or out of our market altogether. Given the quite small size of our market, I can't blame them for doing so and it only puts the makers wealthy enough to be able to ride this out in a monopoly position.
Incidently and I don't know if this also occurred in UK Production, our Clubman models had a crumple zone in them, the very first of them didn't and I think it was early in 1971 that we got them. By the way, the scale of production here was quite small compared to the UK, that they would usually only have 2 types of Mini in production at any point in time, so when they introduced the Clubman here, they dropped the Round Nose types, last of them was made in 1970.