I saw them operating out of London City yesterday (Thursday 26th) morning. Are they going to be based there for the contest ? They were all gone by the evening.
In another thread on the same subject (but in the Private Flying forum) it was mentioned they were going to use a temporary runway at a disused dock near the airport. Today (Friday), from a distance, I saw on of them appearing to land somewhere just north of LCY. Looking at a map, all I can see in that area are some playing fields - surely it's not there?