How old is your friend?.
I was born in Holland but came away when I was less than a month old and worked in the UK.
Oddly enough I have a friend who was born in Germany but was bought to the UK when he was about a month old.
He got called for German National Service but he was working for a UK bank at the time.
If he had been working for an employer in Germany the employer would have had to keep his job open but there was no such obligation in the UK.
My friend did not even speak German and fortunately the German authorities used some common sense and exempted him.
He would have been of little use to them anyway.
Oschilds