Actually, they can't fly to Asia from anywhere in the EU; the right to open up a base anywhere in Europe applies currently only to inter-EU flights (or any other country with which the EU has an open aviation area); it will apply to the US from October.
I'm not sure whether any such agreements are in place with Asian countries?
However, I was really trying to focus on the commercial sense of doing this; rather than going onto someone else's patch - PARTICULARLY at LHR, it seems to make much more sense to be focused on its own market.(As long as SIPTU will allow them, of course ...)
Although EI has set up a codeshare/feeder agreement with Emirates, I understand that the new HKG/DXB flights are actually with CX from Dubai; they have a flight that goes DXB-BKK-HKG.
Hopefully they will fly to one of these cities within the next 2 years.