ELondonpax if you read VirginBlue's post he mentions daytrips to Bremen. In this case the flight arrives around 1215 and departs at 18:35. Not impossible but not great for a day trip.
However I remember being told before that something like 60% of pax at LCY were inbound from other European destinations so that would make sense to focus on the needs of the German daytripper coming to London rather than the other way around.