What is "netherne-on-the-hill"

Netherne-on-the-Hill is a village in Surrey, England, occupying a plateau once home to Netherne Hospital. The village is across a narrow valley from Hooley in north of the borough of Reigate and Banstead; through the valley runs the Hooley Tunnel cutting and A23, the only road from which the village can be accessed, from two designated side roads; a few metres south of the southern T-junction, the road divides into two grades: the A23 to Redhill, south, and the M23 motorway which has a junction with the M25 motorway within Merstham's boundaries, the former village of the hilltop land. The post town, Coulsdon in Greater London is centred due north.