Re: CORK
I'd have to agree with Cyrano. Cruise Mach No. on the ocean for an A319 is around .76. The procedural separation between a B744 following an A319 on the ocean would therefore be in the region of 40 mins. That's a long time to block up a core track in the middle of a busy east or west flow. The guys in Prestwick would get pretty tired of that scenario!
The only option therefore for an A319 would be either to fly on a non core or random track thereby avoiding the busy flow areas or fly on the core but off peak. On an aircraft that would already be tight enough fuel wise these are fairly draconian options. I can't ever really see the day then that A319's will be a common feature on the ocean.
The idea of BA 75's out of Cork is certainly interesting though!