I dropped out of my previous PhD 4 years ago, because my UK institution had a four year maximum time limit for completion which I didn't meet due to my mental health issues. I'm now recovered and have been working for the last three years in a research position at another university. I would now like to apply to do my PhD part-time in the department where I work.
I think my previous supervisor would give me a reasonable reference as he was sympathetic to my issues, but I am concerned about how it would look to use an academic reference from a qualification I didn't complete. My only alternative would be a generic reference from my undergraduate study director who will not even remember me as I only met him a handful of times and I completed that degree ten years ago.
Which would look best?