How do you refer to someone whose title has changed? I am writing a personal statement for a PhD application and I’d like to refer to my previous lecturer.  He was a Dr. at the time he taught me but he is now a professor at another institution.  

Is there a neat way of referring to someone like this or do I have to go with something clumsy as:


  I was taught by Dr. X (now Prof.) on his course about Y.
The person is now a professor, so refer to them primarily as that.  If you are concerned about confusion, you can add the additional information in the sub-clause, where it reads more smoothly:


  I took course Y from Prof. X, while he was a [lecturer, postdoc, whatever] at [instutition]"