With four aircraft in each of a right and left handed circuit that's a potential fifty odd movements an hour for a start.
8 aircraft doing circuits for an hour or so is hardly as busy as the arrivals and departures at Heathrow. Don't forget this is constant arrivals and departures, 7 days a week so I don't think you can really compare the two.
Add in those departing/arriving from Predannack
There was no mention of Predannack in his statement.
I also think you will find that Bessbrook Mill was the busiest Heliport at one time.