Thanks Gavin. However, whilst that works great in theory, the real problem seems to be that no carrier is keen to move out of T3 (unless you know differently). The candidates are:
RYANAIR - Highly unlikely to move. Love T3 and its proximity to the runways. Growth forecast at 33% for next financial year alone. Entrenched.
FLYBE / LOGANAIR / STOBART (IOM) - Another large T3 incumbent. Part of T3 is configured as a minihub for them. Highly unlikely to move.
ONEWORLD (and associated carriers):
British Airways
Sun-Air of Scandinavia (BA franchise)
Vueling
Iberia Express
American Airlines
With the BA / Oneworld group, one would probably expect these carriers to remain together so a bloc move would be required? One potential chink of light is that Oneworld carrier Finnair operates from T1 ... could (at least) one of the others be persuaded to join them there? Vueling could become amenable to relocation if rumours of future based aircraft hold any truth ... where would T3 fit them?
AIR FRANCE / KLM - On paper, persuading this pair to relocate would be ideal. But the situation seems to be that they're not interested in moving.
MICELLANY
Adria Airways
Tailwind Airlines
Denim Air
These three carriers operated four regular weekly flights between them in Summer 2015, and those outside peak hours. Moving these would not resolve any T3 capacity issues.
In the light of projected growth by Ryanair, FlyBe and Vueling in particular, something will have to give. But who will blink first? Are any of these carriers / groupings anywhere close to being persuaded / incentivised to switch terminal in the near term?
[Note: Obviously, American Airlines would likely move to T2 for US PDC, but that seems at least a couple of years away, maybe considerably longer].