David:
Why on earth would a single rotation to LCY work?
At the risk of stating the blindingly obvious, the prime users of LCY are business passengers (this is reflected in the destinations served from LCY, the aircraft types, and the landing fees).
Consider a business passenger from Cork going to London (or vice versa) for a meeting:
Option (a): I can fly over in the morning and back home in the evening, or if my meeting is starting/finishing at another time there's enough frequency of flights to let me work around that.
Option (b): I have to plan my meeting time around the flight schedule, and I have to stay overnight because there's only one daily service.
Even if your meeting is in the City or Canary Wharf, I submit you're more likely to go for option (a).
Sure, not all business passengers are on same-day trips, but an airline needs *at least* a well-timed morning and evening rotation to be competitive for the short-haul business market.
Whether there is sufficient business traffic to enable a reasonable ORK-LCY service given the competition to the other London airports remains to be seen (presumably what LCY are about with their survey) but a once-daily would be doomed to failure from the start.