Here’s what I think is going on: you are a typical middle class British person, you approach door, lift, end of queue a bit timorously, looking round, seeing if it’s all clear, etc. before going ahead (I am American by birth, but have lived in UK for decades & this, frankly, drives me crazy) Germans and many other nationalities in a similar situation see, queue, lift, door etc, and just know that right, that’s where I need to go. They see you,approaching rather uncertainly, looking around, etc, as someone who, in contrast to them, is NOT sure where you are going, maybe waiting for someone else, etc. So the step forward in front of you. Both nationalities are mis-reading the situation, but the German (or whoever) does not view you as a British person, but someone not quite sure of where you are going. To them, it’s not rude, but to you it is. You need to become aware of cultural norms, ESPECIALLY your own!
Queueing norms are very cultural-specific!