Thank you for the question, and for being the second poster on this forum!

The simple answer is that, as far as we know, there are no surviving design plans for the garden layout. It seems that the garden developed over many years -- centuries even -- with the formal layout as it is today, dating from the early 20th century.

Before the Willis Flemings took over Chilworth manor from the Serle family, there was already a substantial garden there -- a local guidebook of 1818 says there was then a large extent of pleasure grounds in which were "beautiful gardens" and shrubberies. We hold an original plan from 1755 (see here), which shows a garden on the site.

The first mention of a Willis Fleming living there is John Brown Willis Fleming, in 1848. By 1853, the house was leased to the banker George Atherley (1818-1883), and in a letter to Atherley, 11 Feb 1853, JBWF discussed changes to the garden:

"In the total absence of any estimates it is almost impossible to make any terms for the construction of the wall round the new garden. .... As far as I can now judge I think, if you were to build the wall twelve feet high taking a lease for three years without any additional rent for the land, it would be a very equitable transaction on both sides. ... If you will plant the fruit trees, I shall be happy to take then at a valuation, whenever you may quit, according to the schedule contained in the Printed Agreements now generally adopted on my estates. There are some old fig trees, which unless too old are well worth removing, they are now against the wall in the old kitchen garden. Would you permit me to suggest the propriety of adopting the French method in the pear & apple trees which you may wish to plant in the new garden."

In 1863, Chilworth House was leased to the Fleming Estate's steward, Richard Pink. The lease document contains a plan that shows the layout of the garden and grounds, as well as the existence of the two 'circular 'beehive' entrance lodges. JBWF returned to live there soon after he remarried in 1868. The WFs stayed there until 1913, and lived there again from 1925-1944.

The house itself was remodelled and enlarged, piecemeal, between 1890 and 1904. It seems that at this time the gardens and grounds were radically altered -- terraces were formed, garden ornaments were brought from North Stoneham, specimen trees and avenues were planted, including the circular 'deer ring'. See these two photographs from around 1906, which shows the (presumably new) fountain and walk that leads to the woodland area, and pond:




The Hampshire Gardens Trust have researched the gardens in quite a lot of detail, and have interpreted details using the ordnance survey maps.

A recent stay at Chilworth sparked an interest in the Gardens - and the Deer Ring in particular.
As noted by Harry, the Hampshire Gardens Trust produced a survey of the Manor, in which the most exact date for the origin of the Ring is given as 1893. Maps from 1896 and 1910 don't show the feature - it probably hadn't developed sufficiently to warrant recording. The 1906 picture in Harry's posting would tend to confirm this as there's no significant feature at the end of the yew allee.
A second ring was planted during the 1960s (no exact date appears in the HGT document) although there is no record of it on a 1985 map included in the same document. No reason is given for its planting - perhaps it was intended as a second 'Deer Ring'?

Searches for Chilworth on the web revealed a link to the weblog of a man called Hugh Macdougall. His 'blog contains a brief anecdote concerning his stay at the Manor in the early 1980s.
Have a look at:

hughmacdougall.com/category/where-can-i-go-and-what-can-i-see-in-the-world/

Scroll down the screen to find the entry entitled 'A Beautiful Cottage'

Subsequent correspondence with Mr Macdougall has produced a fascinating set of photographs which he took of the gardens during his stay at the Manor.
I will include these in a subsequent posting

John, this is really interesting and Hugh Macdougall's wonderful photographs are revealing and rather atmospheric. My instinct is that the caryatid statues did indeed come from North Stoneham. It seems that quite a lot of the other architectural pieces in the gardens at Chilworth, such as many of the urns, have gone missing in recent years?

We have some aerial photos of the house and garden taken around 1930, which I will post here later.

And here is a clear view of the herbaceous border, also in 1912:

I think these views date from the 1930s: