The declared distances should be about right although they're really meant for helicopters carrying out instrument approaches so for VFR ops they could be increased. No entry about circuit procedures so presumably LHC on every runway.
Pooleys 1980 gives:
10/28 582m x 30m but licensed LDA for helis on runway 28 was 436m
18/36 381m x 30m
So roughly the same as Netherthorpe.
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