Ethiopian
ET's country manager for the UK seems to be looking beyond LHR for extra capacity. Realistically this is likely to mean MAN, LGW, EDI but I don't know what they are looking to tap into. ADD (which can only mean ET from MAN) was part of a "story" in the MEN a year or so ago. Link and key extract below.
https://www.routesonline.com/news/29/br ... expansion/
Q: Will Heathrow be the main focus or, given its slot constraints, is the airline planning to grow its network elsewhere?
A: Additional frequency from LHR, introduction of second UK airport or a mixture of both are options that we are currently working hard to introduce as we need to bring more capacity to the market to achieve our long-term growth ambitions in the UK market.