what is so important about this estate?
It was developed as a weekend retreat, that had views of the Surrey landscape.
Denbies
A farmhouse originally owned by John Denby in the mid-16th century, after whom the estate is named, stood at the heart of Denbies. The lands were sold by William Wakefield (or Wakeford) to Jonathan Tyers in 1734, to be developed as a weekend retreat. Tyers was the owner of London's Vauxhall Gardens – known at that time as New Spring Gardens – and was responsible for developing that venue into a "fashionable place of evening entertainment". 
what is denbies? It is a large estate where is it located? To the northwest of Dorking in Surrey, England
wiki:18921808
Denbies [SEP] History
Tyers installed a well beside the house; a note in "The Gentleman's Magazine" of 1781 gives the well's measurements, recorded on 4 October 1764, as being in diameter and reaching a depth of . On that day it contained water to a depth of supplied from a spring. The front of the house had a pediment in the central wing decorated with a coat of arms; the rooms were not large but were conveniently situated. According to historian Brian Allen the house was not architecturally significant and scant information is available about it; the garden established by Tyers, however, gained notoriety.