I think the driver would have been most at risk, along with any passengers in the front row at the top, but it seems the bus mainly hit on its left side. Still, anyone sitting on the left side in the front row at the top could have come off very badly, I hope that's not the case.
A newer article, this one says six injured, not nine:
https://www.theguardian.com/uk-news/2017/aug/10/bus-crashes-shop-south-london-clapham-injured
I think the driver would have been most at risk, along with any passengers in the front row at the top, but it seems the bus mainly hit on its left side. Still, anyone sitting on the left side in the front row at the top could have come off very badly, I hope that's not the case.