Would I be right in guessing the route carries circa 50,000 per annum?
Close enough, 47,885 last year, which is a considerable number given the competition from Ryanair with routes to LPL and LBA. It is the fifth busiest route at the airport after STN, LTN, LGW and LPL.
I think its a given that if its Aer Lingus it will be under the EI Regional brand. Would have previously said that RE wouldn't compete with themselves out of Galway but given that they are now doing it at Shannon, they may well be willing to do likewise at Knock. However, my preference would remain flybe as it would help them to improve their brand awareness in this part of the world, I think there is room for them to expand into other routes from Knock and maybe eventually base a plane here.
I like Aer Lingus but my opinion is that they have never properly given Knock the chance it deserves and are unlikely to start doing so now. If they set up MAN it would probably just be a one off route with no real possibility for future expansion from the airline. That is why we have UK carriers like bmibaby and flybe competing with Ryanair here by flying to the major UK airports when at Shannon and Cork it is Aer Lingus doing the competing on these routes.