CmdrVimes, sorry to hear about the accident. If his insurance co. is a large, reputable company, they should be willing to pay for a full replacement part and not just fill the hole with some bondo.
When my Mini needed some work done, I took it to Manassas European Autobody. They were recommended by Mini of Sterling. They did excellent work. It is a bit out of the way from MD, but for piece of mind knowing the job will be done right, you may want to give them a call. PM/e-mail me if you want their address and phone number.