That's what I want the problem is the link you sent with instructions is in german, and I only speak English ;-) But thanks for reply and idea.
The link is not german, it automatically localizes, but what it is based on I don't know. But something on your end must point to german. Even when I hardcode another locale in the link (en-uk) it changes to Danish for, which makes since I am Danish in Denmark, but still I don't know why.
Anyway, It is not that difficult. Just add the city for gmt in world clock (clock app) on your iphone and it will show up in world clock app on watch, but more important also as a complication you can add to your watch face. You can also change the abbreviation for the city on the iphone.