If my memory serves me correctly the chap in question arrived after the move to TC had taken place, so that was after '93.
The person in question is the person who has now moved to Swiss ATC, I know i did his board as the examiner with Bert as the SRG inspector (Chairman). He (AB) had never seen 23, it was an interesting board with lots of prompts and questions, he did very well and passed with flying colours, we both remember it to this day.