When Kahmann, from North Rhine-Westphalia, started his degree at the Cologne University of Applied Sciences it was 1973, Willy Brandt was still the chancellor, Watergate was setting the international media alight - and he was a full four decades younger.
While most students - especially in Germany - take a few years to complete a degree, life got in the way for Kahmann, who told the paper that he “de-matriculated and re-matriculated three times between then and now.”
Kahmann's student ID number was six figures long when he got his first card in 1973 - new students now have an eight-figure number.
“It was nice to have finally managed to get it done,” he added. Relief indeed, after sitting a grand total of 68 exams over his academic career.
“If I had moved to Cologne I would have just got my studying done,” but instead the 61-year-old father decided to commute in from the nearby town of Siegburg, where his girlfriend, football club and bowling team all kept him rooted at home.
The first time Kahmann put his diploma on hold, he broke his leg playing football. The second time, it was 1984 and his daughter was born so he took time out to help raise her. “Then in 2004 when student fees were introduced, I de-matriculated again.”
In 2011, the fee system changed and Kahmann found himself with his nose in a book one again. But this time, it was for real – he earned his diploma a year later, even though the university did not even run the course anymore.
There would be downsides to being a graduate though, he said. “Paying for public transport and not getting reduced tickets for the zoo,” being two of Kahmann's complaints.
Despite taking so long, Kahmann has been working since 1978 as a freelance engineer and draftsman.
“My daughter told me recently that she, aged 27 and with a brilliant job, wants to go and study,” he said. “I just told her that she should see it through to the end.”