If the DVLA ask for an assessment they can send your dad to a recognized centre where his ability to drive will be sorted out and any recommendations can be made.....doesn't mean he can't drive but his car may need to be adapted. I went through this test this week after having my right lower leg amputated 4 weeks ago. I now have a carbon/kevlar leg and I'm still able to drive a manual car perfectly. Hope this helps.
Regards Stebbo
