Not that unusual actually. I was a staff pilot on Doms 87-92 and quite a few of the LLTS Nav Instructors were quite useful pilots. With one of them I usually had my hands on the control column twice each sortie - once to unlock the flying controls before take-off and once to lock them again after landing. My Navigating was far more dangerous than his flying.
While I was holding in the Nav Sim at FY prior to starting my OCU, I was invited to participate in an overnight Dom SCT to Wildenwrath - we had to pick up the German Exchange Officer who had been home on business. We arrived at lunchtime - a few beers were followed by a trip to the NAAFI to buy our Duty Free which was promptly drunk during the afternoon. Another batch of Duty Free was bought in time for the bar to re-open in the evening. As the bar closed, our pilot met an old mate leading to our duty frees being consumed again. Next morning, our pilot was not feeling particularly well but fortunately the Nav Instructor was working his way towards a CPL, and he flew us home with me (a group 1 Nav) quickly learning about airways flying in the back. The pilot enjoyed a good sleep for most of the way home.