Boslandew, thanks for some interesting input.
Note your comment "set-up costs of a new heli operation would be considerable". Isn't that exactly what the planners should have been considering? Don't understand how the operator was losing money, but that's another story.
Had a long chat with an architect a few years ago who explained there was provision for planners to refuse permission on the grounds that existing facilities were adequate (e.g. number of supermarkets). But, planners never did this, because the applicant could appeal, would probably win their appeal and would claim their costs from the planning authority.
I can't help thinking if the Isles of Scilly were 28 miles off the Scottish coast the outcome would be different.